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<a href="async__file__logger_8cpp.html">Go to the documentation of this file.</a><div class="fragment"><div class="line"><a id="l00001" name="l00001"></a><span class="lineno">    1</span><span class="comment">/* Flow</span></div>
<div class="line"><a id="l00002" name="l00002"></a><span class="lineno">    2</span><span class="comment"> * Copyright 2023 Akamai Technologies, Inc.</span></div>
<div class="line"><a id="l00003" name="l00003"></a><span class="lineno">    3</span><span class="comment"> *</span></div>
<div class="line"><a id="l00004" name="l00004"></a><span class="lineno">    4</span><span class="comment"> * Licensed under the Apache License, Version 2.0 (the</span></div>
<div class="line"><a id="l00005" name="l00005"></a><span class="lineno">    5</span><span class="comment"> * &quot;License&quot;); you may not use this file except in</span></div>
<div class="line"><a id="l00006" name="l00006"></a><span class="lineno">    6</span><span class="comment"> * compliance with the License.  You may obtain a copy</span></div>
<div class="line"><a id="l00007" name="l00007"></a><span class="lineno">    7</span><span class="comment"> * of the License at</span></div>
<div class="line"><a id="l00008" name="l00008"></a><span class="lineno">    8</span><span class="comment"> *</span></div>
<div class="line"><a id="l00009" name="l00009"></a><span class="lineno">    9</span><span class="comment"> *   https://www.apache.org/licenses/LICENSE-2.0</span></div>
<div class="line"><a id="l00010" name="l00010"></a><span class="lineno">   10</span><span class="comment"> *</span></div>
<div class="line"><a id="l00011" name="l00011"></a><span class="lineno">   11</span><span class="comment"> * Unless required by applicable law or agreed to in</span></div>
<div class="line"><a id="l00012" name="l00012"></a><span class="lineno">   12</span><span class="comment"> * writing, software distributed under the License is</span></div>
<div class="line"><a id="l00013" name="l00013"></a><span class="lineno">   13</span><span class="comment"> * distributed on an &quot;AS IS&quot; BASIS, WITHOUT WARRANTIES OR</span></div>
<div class="line"><a id="l00014" name="l00014"></a><span class="lineno">   14</span><span class="comment"> * CONDITIONS OF ANY KIND, either express or implied.</span></div>
<div class="line"><a id="l00015" name="l00015"></a><span class="lineno">   15</span><span class="comment"> * See the License for the specific language governing</span></div>
<div class="line"><a id="l00016" name="l00016"></a><span class="lineno">   16</span><span class="comment"> * permissions and limitations under the License. */</span></div>
<div class="line"><a id="l00017" name="l00017"></a><span class="lineno">   17</span><span class="comment"></span> </div>
<div class="line"><a id="l00018" name="l00018"></a><span class="lineno">   18</span><span class="comment">/// @file</span></div>
<div class="line"><a id="l00019" name="l00019"></a><span class="lineno">   19</span><span class="comment"></span><span class="preprocessor">#include &quot;<a class="code" href="async__file__logger_8hpp.html">flow/log/async_file_logger.hpp</a>&quot;</span></div>
<div class="line"><a id="l00020" name="l00020"></a><span class="lineno">   20</span><span class="preprocessor">#include &quot;<a class="code" href="serial__file__logger_8hpp.html">flow/log/detail/serial_file_logger.hpp</a>&quot;</span></div>
<div class="line"><a id="l00021" name="l00021"></a><span class="lineno">   21</span><span class="preprocessor">#include &quot;flow/error/error.hpp&quot;</span></div>
<div class="line"><a id="l00022" name="l00022"></a><span class="lineno">   22</span><span class="preprocessor">#include &lt;boost/move/make_unique.hpp&gt;</span></div>
<div class="line"><a id="l00023" name="l00023"></a><span class="lineno">   23</span><span class="preprocessor">#include &lt;algorithm&gt;</span></div>
<div class="line"><a id="l00024" name="l00024"></a><span class="lineno">   24</span><span class="preprocessor">#include &lt;memory&gt;</span></div>
<div class="line"><a id="l00025" name="l00025"></a><span class="lineno">   25</span><span class="preprocessor">#include &lt;utility&gt;</span></div>
<div class="line"><a id="l00026" name="l00026"></a><span class="lineno">   26</span> </div>
<div class="line"><a id="l00027" name="l00027"></a><span class="lineno"><a class="line" href="namespaceflow_1_1log.html">   27</a></span><span class="keyword">namespace </span><a class="code hl_namespace" href="namespaceflow_1_1log.html">flow::log</a></div>
<div class="line"><a id="l00028" name="l00028"></a><span class="lineno">   28</span>{</div>
<div class="line"><a id="l00029" name="l00029"></a><span class="lineno">   29</span> </div>
<div class="line"><a id="l00030" name="l00030"></a><span class="lineno">   30</span><span class="comment">// Implementations.</span></div>
<div class="line"><a id="l00031" name="l00031"></a><span class="lineno">   31</span> </div>
<div class="line"><a id="l00032" name="l00032"></a><span class="lineno"><a class="line" href="classflow_1_1log_1_1Async__file__logger.html#aec2b1796c81b020cacea493e21e19562">   32</a></span><a class="code hl_function" href="classflow_1_1log_1_1Async__file__logger.html#aec2b1796c81b020cacea493e21e19562">Async_file_logger::Async_file_logger</a>(<a class="code hl_class" href="classflow_1_1log_1_1Logger.html">Logger</a>* backup_logger_ptr,</div>
<div class="line"><a id="l00033" name="l00033"></a><span class="lineno">   33</span>                                     <a class="code hl_class" href="classflow_1_1log_1_1Config.html">Config</a>* config, <span class="keyword">const</span> fs::path&amp; log_path,</div>
<div class="line"><a id="l00034" name="l00034"></a><span class="lineno">   34</span>                                     <span class="keywordtype">bool</span> capture_rotate_signals_internally) :</div>
<div class="line"><a id="l00035" name="l00035"></a><span class="lineno">   35</span>  <span class="comment">/* Set up the logging *about our real attempts at file logging*, probably to a Simple_ostream_logger/cout;</span></div>
<div class="line"><a id="l00036" name="l00036"></a><span class="lineno">   36</span><span class="comment">   * or to null (meaning no such logging).  Either way we will still attempt to actually log user-requested messages</span></div>
<div class="line"><a id="l00037" name="l00037"></a><span class="lineno">   37</span><span class="comment">   * to log_path! */</span></div>
<div class="line"><a id="l00038" name="l00038"></a><span class="lineno">   38</span>  <a class="code hl_class" href="classflow_1_1log_1_1Log__context.html">Log_context</a>(backup_logger_ptr, <a class="code hl_enumeration" href="namespaceflow.html#a3938730ab4b89daf13d027a5f620e7ce">Flow_log_component</a>::S_LOG),</div>
<div class="line"><a id="l00039" name="l00039"></a><span class="lineno">   39</span>  m_config(config), <span class="comment">// Save pointer, not copy, of the config given to us.  Hence thread safety is a thing.</span></div>
<div class="line"><a id="l00040" name="l00040"></a><span class="lineno">   40</span> </div>
<div class="line"><a id="l00041" name="l00041"></a><span class="lineno">   41</span>  <span class="comment">/* Set up throttling algorithm, which is always-on (see class doc header discussion).</span></div>
<div class="line"><a id="l00042" name="l00042"></a><span class="lineno">   42</span><span class="comment">   * Reminder that its output will be ignored, until/unless user calls throttling_cfg(true, ...).  They can then</span></div>
<div class="line"><a id="l00043" name="l00043"></a><span class="lineno">   43</span><span class="comment">   * set their own config values as well (or reuse this default which they can access via throttling_cfg() accessor). */</span></div>
<div class="line"><a id="l00044" name="l00044"></a><span class="lineno">   44</span>  m_throttling_cfg({ <a class="code hl_variable" href="structflow_1_1log_1_1Async__file__logger_1_1Throttling__cfg.html#a72a52accb11b29307dad69748e133818">Throttling_cfg::S_HI_LIMIT_DEFAULT</a> }),</div>
<div class="line"><a id="l00045" name="l00045"></a><span class="lineno">   45</span>  m_pending_logs_sz(0), <span class="comment">// No memory used yet by pending messages.</span></div>
<div class="line"><a id="l00046" name="l00046"></a><span class="lineno">   46</span>  m_throttling_now(<span class="keyword">false</span>), <span class="comment">// No throttling yet.</span></div>
<div class="line"><a id="l00047" name="l00047"></a><span class="lineno">   47</span>  m_throttling_active(<span class="keyword">false</span>),</div>
<div class="line"><a id="l00048" name="l00048"></a><span class="lineno">   48</span> </div>
<div class="line"><a id="l00049" name="l00049"></a><span class="lineno">   49</span>  <span class="comment">// Any I/O operations done here are the only ones not done from m_async_worker thread.</span></div>
<div class="line"><a id="l00050" name="l00050"></a><span class="lineno">   50</span>  m_serial_logger(boost::movelib::make_unique&lt;Serial_file_logger&gt;(get_logger(), m_config, log_path)),</div>
<div class="line"><a id="l00051" name="l00051"></a><span class="lineno">   51</span>  <span class="comment">/* ...Speaking of which: start the worker thread right now; synchronously; return from this ctor once it has</span></div>
<div class="line"><a id="l00052" name="l00052"></a><span class="lineno">   52</span><span class="comment">   * certified it is up.  It will log (to *backup_logger_ptr if not null) about starting up right here, too, which</span></div>
<div class="line"><a id="l00053" name="l00053"></a><span class="lineno">   53</span><span class="comment">   * in practice would be the bulk of INFO-or-less-verbose log lines from us in my experience. */</span></div>
<div class="line"><a id="l00054" name="l00054"></a><span class="lineno">   54</span>  m_async_worker(backup_logger_ptr, <a class="code hl_function" href="namespaceflow_1_1util.html#a685b86585da2fa5186f51854e7ae1561">util::ostream_op_string</a>(<span class="stringliteral">&quot;ASFL-&quot;</span>, <span class="keyword">this</span>)),</div>
<div class="line"><a id="l00055" name="l00055"></a><span class="lineno">   55</span>  <span class="comment">/* Set up a signal set object; this is a no-op until we .add() signals to it (which we may or may not do).</span></div>
<div class="line"><a id="l00056" name="l00056"></a><span class="lineno">   56</span><span class="comment">   * Whether we do or not is more significant than merely whether whatever handler we&#39;d later register</span></div>
<div class="line"><a id="l00057" name="l00057"></a><span class="lineno">   57</span><span class="comment">   * via m_signal_set.async_wait() will be called; if we .add() zero signals, then IF some non-boost.asio</span></div>
<div class="line"><a id="l00058" name="l00058"></a><span class="lineno">   58</span><span class="comment">   * signal handler is currently registered (such as some default OS handler; or the user&#39;s non-boost.asio handler)</span></div>
<div class="line"><a id="l00059" name="l00059"></a><span class="lineno">   59</span><span class="comment">   * (or will be registered in the future) will continue to work undisturbed.  If, however, we .add() one or more</span></div>
<div class="line"><a id="l00060" name="l00060"></a><span class="lineno">   60</span><span class="comment">   * signals (or, equivalently, list 1 or more signal numbers right here in the constructor call),</span></div>
<div class="line"><a id="l00061" name="l00061"></a><span class="lineno">   61</span><span class="comment">   * then we will REPLACE such non-boost.asio handlers with boost.asio&#39;s mechanism.  (This behavior is</span></div>
<div class="line"><a id="l00062" name="l00062"></a><span class="lineno">   62</span><span class="comment">   * explicitly documented in boost.asio docs.)  Therefore we must be careful not to mindlessly .add() handler(s),</span></div>
<div class="line"><a id="l00063" name="l00063"></a><span class="lineno">   63</span><span class="comment">   * and/or (equivalently) list 1 or more signal numbers in this constructor call here.  The choice will be left to</span></div>
<div class="line"><a id="l00064" name="l00064"></a><span class="lineno">   64</span><span class="comment">   * later code which will .add() or not .add() deliberately.  (Copy/paste warning: This cmnt was copy-pasted from some</span></div>
<div class="line"><a id="l00065" name="l00065"></a><span class="lineno">   65</span><span class="comment">   * vaguely similar code in flow::net_flow; but the 2 modules are barely related if at all, so....) */</span></div>
<div class="line"><a id="l00066" name="l00066"></a><span class="lineno">   66</span>  m_signal_set(*(m_async_worker.task_engine()))</div>
<div class="line"><a id="l00067" name="l00067"></a><span class="lineno">   67</span>{</div>
<div class="line"><a id="l00068" name="l00068"></a><span class="lineno">   68</span>  m_async_worker.start(<a class="code hl_function" href="namespaceflow_1_1async.html#a227e64eb71ec278f19d679d8411db627">flow::async::reset_this_thread_pinning</a>);</div>
<div class="line"><a id="l00069" name="l00069"></a><span class="lineno">   69</span>  <span class="comment">// Don&#39;t inherit any strange core-affinity!  ^-- Worker must float free.</span></div>
<div class="line"><a id="l00070" name="l00070"></a><span class="lineno">   70</span> </div>
<div class="line"><a id="l00071" name="l00071"></a><span class="lineno">   71</span>  <a class="code hl_define" href="log_8hpp.html#a325fdd4b5cf0be49b37d3b7b7c29070d">FLOW_LOG_INFO</a>(<span class="stringliteral">&quot;Async_file_logger [&quot;</span> &lt;&lt; <span class="keyword">this</span> &lt;&lt; <span class="stringliteral">&quot;]: &quot;</span></div>
<div class="line"><a id="l00072" name="l00072"></a><span class="lineno">   72</span>                <span class="stringliteral">&quot;Log-writing worker thread(s) have started around now; ready to work.&quot;</span>);</div>
<div class="line"><a id="l00073" name="l00073"></a><span class="lineno">   73</span> </div>
<div class="line"><a id="l00074" name="l00074"></a><span class="lineno">   74</span>  <span class="comment">// Immediately open file in worker thread.  Could be lazy about it but might as well log about any issue ASAP.</span></div>
<div class="line"><a id="l00075" name="l00075"></a><span class="lineno">   75</span>  log_flush_and_reopen(<span class="keyword">false</span>); <span class="comment">// Do it synchronously for good measure; doesn&#39;t matter but the reduced entropy is nice.</span></div>
<div class="line"><a id="l00076" name="l00076"></a><span class="lineno">   76</span> </div>
<div class="line"><a id="l00077" name="l00077"></a><span class="lineno">   77</span>  <span class="keywordflow">if</span> (capture_rotate_signals_internally)</div>
<div class="line"><a id="l00078" name="l00078"></a><span class="lineno">   78</span>  {</div>
<div class="line"><a id="l00079" name="l00079"></a><span class="lineno">   79</span>    <a class="code hl_define" href="log_8hpp.html#a325fdd4b5cf0be49b37d3b7b7c29070d">FLOW_LOG_INFO</a>(<span class="stringliteral">&quot;Setting up internal log-rotate-reopening signal handler.  &quot;</span></div>
<div class="line"><a id="l00080" name="l00080"></a><span class="lineno">   80</span>                  <span class="stringliteral">&quot;CAUTION!  User program MUST avoid using non-boost::asio::signal_set signal handling!  &quot;</span></div>
<div class="line"><a id="l00081" name="l00081"></a><span class="lineno">   81</span>                  <span class="stringliteral">&quot;If it does use non-boost.asio, behavior is undefined.&quot;</span>);</div>
<div class="line"><a id="l00082" name="l00082"></a><span class="lineno">   82</span> </div>
<div class="line"><a id="l00083" name="l00083"></a><span class="lineno">   83</span>    <span class="comment">// Add the classic log-rotation-inducing signal numbers.</span></div>
<div class="line"><a id="l00084" name="l00084"></a><span class="lineno">   84</span>    m_signal_set.add(SIGHUP);</div>
<div class="line"><a id="l00085" name="l00085"></a><span class="lineno">   85</span> </div>
<div class="line"><a id="l00086" name="l00086"></a><span class="lineno">   86</span>    <span class="comment">/* At this point, receiving those signals will NOT do whatever default behavior would happen -- but I believe</span></div>
<div class="line"><a id="l00087" name="l00087"></a><span class="lineno">   87</span><span class="comment">     * that unlike for SIGTERM/etc. the default behavior is no-op.  Before actually reporting successful initialization</span></div>
<div class="line"><a id="l00088" name="l00088"></a><span class="lineno">   88</span><span class="comment">     * by exiting constructor, set up the handler that&#39;ll be called upon receiving the signals. */</span></div>
<div class="line"><a id="l00089" name="l00089"></a><span class="lineno">   89</span> </div>
<div class="line"><a id="l00090" name="l00090"></a><span class="lineno">   90</span>    <span class="comment">/* this-&gt;impl_log_flush_and_reopen() will be called on signal (or error).</span></div>
<div class="line"><a id="l00091" name="l00091"></a><span class="lineno">   91</span><span class="comment">     * Note that that function&#39;s contract (from its doc comment) is it must execute in m_async_worker (see</span></div>
<div class="line"><a id="l00092" name="l00092"></a><span class="lineno">   92</span><span class="comment">     * m_signal_set() init above in the init section of ctor).</span></div>
<div class="line"><a id="l00093" name="l00093"></a><span class="lineno">   93</span><span class="comment">     * Indeed boost::asio::io_context semantics guarantee it&#39;ll run in m_async_worker (not some</span></div>
<div class="line"><a id="l00094" name="l00094"></a><span class="lineno">   94</span><span class="comment">     * no-man&#39;s-land signal handler thread of execution, as one might fear could be the case) for the same reason</span></div>
<div class="line"><a id="l00095" name="l00095"></a><span class="lineno">   95</span><span class="comment">     * the various post()ed tasks will run in m_async_worker. */</span></div>
<div class="line"><a id="l00096" name="l00096"></a><span class="lineno">   96</span>    m_signal_set.async_wait([<span class="keyword">this</span>](<span class="keyword">const</span> <a class="code hl_typedef" href="namespaceflow.html#a29eaaa9d0fac4ce87d8b969222dbed09">Error_code</a>&amp; sys_err_code, <span class="keywordtype">int</span> sig_number)</div>
<div class="line"><a id="l00097" name="l00097"></a><span class="lineno">   97</span>    {</div>
<div class="line"><a id="l00098" name="l00098"></a><span class="lineno">   98</span>      on_rotate_signal(sys_err_code, sig_number);</div>
<div class="line"><a id="l00099" name="l00099"></a><span class="lineno">   99</span>    });</div>
<div class="line"><a id="l00100" name="l00100"></a><span class="lineno">  100</span>  } <span class="comment">// if (capture_rotate_signals_internally)</span></div>
<div class="line"><a id="l00101" name="l00101"></a><span class="lineno">  101</span>  <span class="comment">/* else if (!capture_rotate_signals_internally)</span></div>
<div class="line"><a id="l00102" name="l00102"></a><span class="lineno">  102</span><span class="comment">   * {</span></div>
<div class="line"><a id="l00103" name="l00103"></a><span class="lineno">  103</span><span class="comment">   *   Do NOT .add() anything; and don&#39;t async_wait() anything.  As noted in comment at m_signal_set construction time,</span></div>
<div class="line"><a id="l00104" name="l00104"></a><span class="lineno">  104</span><span class="comment">   *   .add() does more than make it possible to .async_wait().  It also replaces any default OS or user&#39;s own</span></div>
<div class="line"><a id="l00105" name="l00105"></a><span class="lineno">  105</span><span class="comment">   *   non-boost.asio signal handling machinery with boost.asio&#39;s signal_set machinery.  That can be quite draconian,</span></div>
<div class="line"><a id="l00106" name="l00106"></a><span class="lineno">  106</span><span class="comment">   *   so user must specifically set that option to true.  If it&#39;s false (in all siblings of *this in entire  app),</span></div>
<div class="line"><a id="l00107" name="l00107"></a><span class="lineno">  107</span><span class="comment">   *   then whatever signal handling machinery the user wants to set up for themselves (or leave at OS&#39;s</span></div>
<div class="line"><a id="l00108" name="l00108"></a><span class="lineno">  108</span><span class="comment">   *   discretion) will remain undisturbed.  By the way, of course, they can use boost.asio machinery themselves too;</span></div>
<div class="line"><a id="l00109" name="l00109"></a><span class="lineno">  109</span><span class="comment">   *   it&#39;s just that doing so would still work even if capture_rotate_signals_internally were true, so that&#39;s</span></div>
<div class="line"><a id="l00110" name="l00110"></a><span class="lineno">  110</span><span class="comment">   *   not the dangerous scenario.  (Copy/paste warning: This cmnt was copy-pasted from some</span></div>
<div class="line"><a id="l00111" name="l00111"></a><span class="lineno">  111</span><span class="comment">   *   vaguely similar code in flow::net_flow; but the 2 modules are barely related if at all, so....)</span></div>
<div class="line"><a id="l00112" name="l00112"></a><span class="lineno">  112</span><span class="comment">   * } */</span></div>
<div class="line"><a id="l00113" name="l00113"></a><span class="lineno">  113</span>} <span class="comment">// Async_file_logger::Async_file_logger()</span></div>
<div class="line"><a id="l00114" name="l00114"></a><span class="lineno">  114</span> </div>
<div class="line"><a id="l00115" name="l00115"></a><span class="lineno"><a class="line" href="classflow_1_1log_1_1Async__file__logger.html#ac2080e8abfc2cd9580c84626ae205010">  115</a></span><a class="code hl_struct" href="structflow_1_1log_1_1Async__file__logger_1_1Throttling__cfg.html">Async_file_logger::Throttling_cfg</a> <a class="code hl_function" href="classflow_1_1log_1_1Async__file__logger.html#ac2080e8abfc2cd9580c84626ae205010">Async_file_logger::throttling_cfg</a>()<span class="keyword"> const</span></div>
<div class="line"><a id="l00116" name="l00116"></a><span class="lineno">  116</span><span class="keyword"></span>{</div>
<div class="line"><a id="l00117" name="l00117"></a><span class="lineno">  117</span>  <a class="code hl_typedef" href="classflow_1_1log_1_1Async__file__logger.html#a10757ede565842d0faebf50bc1424610">Lock_guard</a> lock(<a class="code hl_variable" href="classflow_1_1log_1_1Async__file__logger.html#a99cd4faff109ef35720fbed9837973dc">m_throttling_mutex</a>);</div>
<div class="line"><a id="l00118" name="l00118"></a><span class="lineno">  118</span>  <span class="keywordflow">return</span> <a class="code hl_variable" href="classflow_1_1log_1_1Async__file__logger.html#aa3d544ab96299a8c2b53b7be485d1a6e">m_throttling_cfg</a>;</div>
<div class="line"><a id="l00119" name="l00119"></a><span class="lineno">  119</span>}</div>
<div class="line"><a id="l00120" name="l00120"></a><span class="lineno">  120</span> </div>
<div class="line"><a id="l00121" name="l00121"></a><span class="lineno"><a class="line" href="classflow_1_1log_1_1Async__file__logger.html#a83cff0d6857a8295e41f90d5e9cab711">  121</a></span><span class="keywordtype">bool</span> <a class="code hl_function" href="classflow_1_1log_1_1Async__file__logger.html#a83cff0d6857a8295e41f90d5e9cab711">Async_file_logger::throttling_active</a>()<span class="keyword"> const</span></div>
<div class="line"><a id="l00122" name="l00122"></a><span class="lineno">  122</span><span class="keyword"></span>{</div>
<div class="line"><a id="l00123" name="l00123"></a><span class="lineno">  123</span>  <span class="keywordflow">return</span> <a class="code hl_variable" href="classflow_1_1log_1_1Async__file__logger.html#a5bbad8cea27134844e73daff014cc82a">m_throttling_active</a>.load(std::memory_order_relaxed);</div>
<div class="line"><a id="l00124" name="l00124"></a><span class="lineno">  124</span>}</div>
<div class="line"><a id="l00125" name="l00125"></a><span class="lineno">  125</span> </div>
<div class="line"><a id="l00126" name="l00126"></a><span class="lineno"><a class="line" href="classflow_1_1log_1_1Async__file__logger.html#a41893a27e7d36c96c224b24420e26dca">  126</a></span><span class="keywordtype">void</span> <a class="code hl_function" href="classflow_1_1log_1_1Async__file__logger.html#ac2080e8abfc2cd9580c84626ae205010">Async_file_logger::throttling_cfg</a>(<span class="keywordtype">bool</span> active, <span class="keyword">const</span> <a class="code hl_struct" href="structflow_1_1log_1_1Async__file__logger_1_1Throttling__cfg.html">Throttling_cfg</a>&amp; cfg)</div>
<div class="line"><a id="l00127" name="l00127"></a><span class="lineno">  127</span>{</div>
<div class="line"><a id="l00128" name="l00128"></a><span class="lineno">  128</span>  assert((cfg.<a class="code hl_variable" href="structflow_1_1log_1_1Async__file__logger_1_1Throttling__cfg.html#a7a30343e388c65594d06baed25b1aaa9">m_hi_limit</a> &gt; 0) &amp;&amp; <span class="stringliteral">&quot;Per contract, hi_limit must be positive.&quot;</span>);</div>
<div class="line"><a id="l00129" name="l00129"></a><span class="lineno">  129</span> </div>
<div class="line"><a id="l00130" name="l00130"></a><span class="lineno">  130</span>  <span class="comment">/* Please see Impl section of class doc header for detailed discussion; also Throttling and m_throttling_states doc</span></div>
<div class="line"><a id="l00131" name="l00131"></a><span class="lineno">  131</span><span class="comment">   * headers.  We just reiterate here that m_throttling_active and m_throttling_cfg are orthogonal to each other;</span></div>
<div class="line"><a id="l00132" name="l00132"></a><span class="lineno">  132</span><span class="comment">   * the latter is thus protected by mutex, while the former is atomic. */</span></div>
<div class="line"><a id="l00133" name="l00133"></a><span class="lineno">  133</span> </div>
<div class="line"><a id="l00134" name="l00134"></a><span class="lineno">  134</span>  <span class="comment">// Deal with `active`.</span></div>
<div class="line"><a id="l00135" name="l00135"></a><span class="lineno">  135</span> </div>
<div class="line"><a id="l00136" name="l00136"></a><span class="lineno">  136</span>  <span class="keyword">const</span> <span class="keyword">auto</span> prev_active = <a class="code hl_variable" href="classflow_1_1log_1_1Async__file__logger.html#a5bbad8cea27134844e73daff014cc82a">m_throttling_active</a>.exchange(active, std::memory_order_relaxed);</div>
<div class="line"><a id="l00137" name="l00137"></a><span class="lineno">  137</span>  <span class="keywordflow">if</span> (prev_active != active)</div>
<div class="line"><a id="l00138" name="l00138"></a><span class="lineno">  138</span>  {</div>
<div class="line"><a id="l00139" name="l00139"></a><span class="lineno">  139</span>    <a class="code hl_define" href="log_8hpp.html#a325fdd4b5cf0be49b37d3b7b7c29070d">FLOW_LOG_INFO</a>(<span class="stringliteral">&quot;Async_file_logger [&quot;</span> &lt;&lt; <span class="keyword">this</span> &lt;&lt; <span class="stringliteral">&quot;]: &quot;</span></div>
<div class="line"><a id="l00140" name="l00140"></a><span class="lineno">  140</span>                  <span class="stringliteral">&quot;Config set: throttling feature active? [&quot;</span> &lt;&lt; prev_active &lt;&lt; <span class="stringliteral">&quot;] =&gt; [&quot;</span> &lt;&lt; active &lt;&lt; <span class="stringliteral">&quot;].&quot;</span>);</div>
<div class="line"><a id="l00141" name="l00141"></a><span class="lineno">  141</span>  }</div>
<div class="line"><a id="l00142" name="l00142"></a><span class="lineno">  142</span>  <span class="comment">/* Subtlety: The un-mutex-protected, relaxed-order-accessed (as opposed to with memory_order_seq_cst)</span></div>
<div class="line"><a id="l00143" name="l00143"></a><span class="lineno">  143</span><span class="comment">   * read/modify/write operation above is the reason we formally forbid this mutator being called concurrently</span></div>
<div class="line"><a id="l00144" name="l00144"></a><span class="lineno">  144</span><span class="comment">   * with itself.  Possibly oddness could occur if the above statement was invoked ~concurrently with itself.</span></div>
<div class="line"><a id="l00145" name="l00145"></a><span class="lineno">  145</span><span class="comment">   * We could instead formally allow it and change the above to seq_cst.  However: (1) in actual reality it&#39;s</span></div>
<div class="line"><a id="l00146" name="l00146"></a><span class="lineno">  146</span><span class="comment">   * very unlikely a reasonable user would want to call this concurrently to self anyway in a realistic dynamic-config</span></div>
<div class="line"><a id="l00147" name="l00147"></a><span class="lineno">  147</span><span class="comment">   * scenario -- usually people use a config-update thread -- so it&#39;s not very important; (2) the existing way</span></div>
<div class="line"><a id="l00148" name="l00148"></a><span class="lineno">  148</span><span class="comment">   * the entire set of config is updated in synchronized fashion, as opposed to separating m_throttling_cfg from</span></div>
<div class="line"><a id="l00149" name="l00149"></a><span class="lineno">  149</span><span class="comment">   * m_throttling_active.  It&#39;s just less entropy, and it hardly matters anyway. */</span></div>
<div class="line"><a id="l00150" name="l00150"></a><span class="lineno">  150</span> </div>
<div class="line"><a id="l00151" name="l00151"></a><span class="lineno">  151</span>  <span class="comment">// Deal with `cfg`.</span></div>
<div class="line"><a id="l00152" name="l00152"></a><span class="lineno">  152</span> </div>
<div class="line"><a id="l00153" name="l00153"></a><span class="lineno">  153</span>  { <span class="comment">// All this-&gt;m_ touched in { here } can concurrently change, unless we lock.</span></div>
<div class="line"><a id="l00154" name="l00154"></a><span class="lineno">  154</span>    <a class="code hl_typedef" href="classflow_1_1log_1_1Async__file__logger.html#a10757ede565842d0faebf50bc1424610">Lock_guard</a> lock(<a class="code hl_variable" href="classflow_1_1log_1_1Async__file__logger.html#a99cd4faff109ef35720fbed9837973dc">m_throttling_mutex</a>);</div>
<div class="line"><a id="l00155" name="l00155"></a><span class="lineno">  155</span> </div>
<div class="line"><a id="l00156" name="l00156"></a><span class="lineno">  156</span>    <span class="keywordflow">if</span> (<a class="code hl_variable" href="classflow_1_1log_1_1Async__file__logger.html#aa3d544ab96299a8c2b53b7be485d1a6e">m_throttling_cfg</a>.<a class="code hl_variable" href="structflow_1_1log_1_1Async__file__logger_1_1Throttling__cfg.html#a7a30343e388c65594d06baed25b1aaa9">m_hi_limit</a> != cfg.<a class="code hl_variable" href="structflow_1_1log_1_1Async__file__logger_1_1Throttling__cfg.html#a7a30343e388c65594d06baed25b1aaa9">m_hi_limit</a>)</div>
<div class="line"><a id="l00157" name="l00157"></a><span class="lineno">  157</span>    {</div>
<div class="line"><a id="l00158" name="l00158"></a><span class="lineno">  158</span>      <span class="keyword">const</span> <span class="keyword">auto</span> prev_throttling_now</div>
<div class="line"><a id="l00159" name="l00159"></a><span class="lineno">  159</span>        = <a class="code hl_variable" href="classflow_1_1log_1_1Async__file__logger.html#aa13ef30bc2d66758c29c31dc76a130aa">m_throttling_now</a>.exchange(<a class="code hl_variable" href="classflow_1_1log_1_1Async__file__logger.html#a7cce9184c2137aa4c2d09894e1aaa7c9">m_pending_logs_sz</a> &gt;= <span class="keyword">static_cast&lt;</span>decltype(<a class="code hl_variable" href="classflow_1_1log_1_1Async__file__logger.html#a7cce9184c2137aa4c2d09894e1aaa7c9">m_pending_logs_sz</a>)<span class="keyword">&gt;</span>(cfg.<a class="code hl_variable" href="structflow_1_1log_1_1Async__file__logger_1_1Throttling__cfg.html#a7a30343e388c65594d06baed25b1aaa9">m_hi_limit</a>),</div>
<div class="line"><a id="l00160" name="l00160"></a><span class="lineno">  160</span>                                    std::memory_order_relaxed);</div>
<div class="line"><a id="l00161" name="l00161"></a><span class="lineno">  161</span>      <span class="comment">// (m_throttling_now cannot change during lock; using .exchange() purely for convenience to grab prev value.)</span></div>
<div class="line"><a id="l00162" name="l00162"></a><span class="lineno">  162</span> </div>
<div class="line"><a id="l00163" name="l00163"></a><span class="lineno">  163</span>      <a class="code hl_define" href="log_8hpp.html#a325fdd4b5cf0be49b37d3b7b7c29070d">FLOW_LOG_INFO</a>(<span class="stringliteral">&quot;Async_file_logger [&quot;</span> &lt;&lt; <span class="keyword">this</span> &lt;&lt; <span class="stringliteral">&quot;]: Config set: &quot;</span></div>
<div class="line"><a id="l00164" name="l00164"></a><span class="lineno">  164</span>                    <span class="stringliteral">&quot;hi_limit [&quot;</span> &lt;&lt; <a class="code hl_variable" href="classflow_1_1log_1_1Async__file__logger.html#aa3d544ab96299a8c2b53b7be485d1a6e">m_throttling_cfg</a>.<a class="code hl_variable" href="structflow_1_1log_1_1Async__file__logger_1_1Throttling__cfg.html#a7a30343e388c65594d06baed25b1aaa9">m_hi_limit</a> &lt;&lt; <span class="stringliteral">&quot;] =&gt; [&quot;</span> &lt;&lt; cfg.<a class="code hl_variable" href="structflow_1_1log_1_1Async__file__logger_1_1Throttling__cfg.html#a7a30343e388c65594d06baed25b1aaa9">m_hi_limit</a> &lt;&lt; <span class="stringliteral">&quot;].  &quot;</span></div>
<div class="line"><a id="l00165" name="l00165"></a><span class="lineno">  165</span>                    <span class="stringliteral">&quot;Mem-use = [&quot;</span> &lt;&lt; <a class="code hl_variable" href="classflow_1_1log_1_1Async__file__logger.html#a7cce9184c2137aa4c2d09894e1aaa7c9">m_pending_logs_sz</a> &lt;&lt; <span class="stringliteral">&quot;]; &quot;</span></div>
<div class="line"><a id="l00166" name="l00166"></a><span class="lineno">  166</span>                    <span class="stringliteral">&quot;throttling? = [&quot;</span> &lt;&lt; prev_throttling_now &lt;&lt; <span class="stringliteral">&quot;] =&gt; [&quot;</span> &lt;&lt; <a class="code hl_variable" href="classflow_1_1log_1_1Async__file__logger.html#aa13ef30bc2d66758c29c31dc76a130aa">m_throttling_now</a> &lt;&lt; <span class="stringliteral">&quot;]; &quot;</span></div>
<div class="line"><a id="l00167" name="l00167"></a><span class="lineno">  167</span>                    <span class="stringliteral">&quot;throttling feature active? = [&quot;</span> &lt;&lt; active &lt;&lt; <span class="stringliteral">&quot;].  &quot;</span></div>
<div class="line"><a id="l00168" name="l00168"></a><span class="lineno">  168</span>                    <span class="stringliteral">&quot;Reminder: `throttling?` shall only be used if `throttling feature active?` is 1.&quot;</span>);</div>
<div class="line"><a id="l00169" name="l00169"></a><span class="lineno">  169</span> </div>
<div class="line"><a id="l00170" name="l00170"></a><span class="lineno">  170</span>      <a class="code hl_variable" href="classflow_1_1log_1_1Async__file__logger.html#aa3d544ab96299a8c2b53b7be485d1a6e">m_throttling_cfg</a>.<a class="code hl_variable" href="structflow_1_1log_1_1Async__file__logger_1_1Throttling__cfg.html#a7a30343e388c65594d06baed25b1aaa9">m_hi_limit</a> = cfg.<a class="code hl_variable" href="structflow_1_1log_1_1Async__file__logger_1_1Throttling__cfg.html#a7a30343e388c65594d06baed25b1aaa9">m_hi_limit</a>;</div>
<div class="line"><a id="l00171" name="l00171"></a><span class="lineno">  171</span>    }</div>
<div class="line"><a id="l00172" name="l00172"></a><span class="lineno">  172</span>    <span class="comment">/* else: As discussed in class doc header: no-op, unless they actually changed something; no state reset.</span></div>
<div class="line"><a id="l00173" name="l00173"></a><span class="lineno">  173</span><span class="comment">     * E.g., perhaps they changed `active` while passing-in `cfg = throttling_cfg()` unchanged. */</span></div>
<div class="line"><a id="l00174" name="l00174"></a><span class="lineno">  174</span>  } <span class="comment">// Lock_guard lock(m_throttling_mutex);</span></div>
<div class="line"><a id="l00175" name="l00175"></a><span class="lineno">  175</span>} <span class="comment">// Async_file_logger::throttling_cfg()</span></div>
<div class="line"><a id="l00176" name="l00176"></a><span class="lineno">  176</span> </div>
<div class="line"><a id="l00177" name="l00177"></a><span class="lineno"><a class="line" href="classflow_1_1log_1_1Async__file__logger.html#ae48ec685cc9951a37bb670dd92fe1f4e">  177</a></span><a class="code hl_function" href="classflow_1_1log_1_1Async__file__logger.html#ae48ec685cc9951a37bb670dd92fe1f4e">Async_file_logger::~Async_file_logger</a>() <span class="comment">// Virtual.</span></div>
<div class="line"><a id="l00178" name="l00178"></a><span class="lineno">  178</span>{</div>
<div class="line"><a id="l00179" name="l00179"></a><span class="lineno">  179</span>  <span class="keyword">using </span><a class="code hl_enumeration" href="namespaceflow_1_1async.html#a0a06794b16b72f2829ce3353557c8485">async::Synchronicity</a>;</div>
<div class="line"><a id="l00180" name="l00180"></a><span class="lineno">  180</span> </div>
<div class="line"><a id="l00181" name="l00181"></a><span class="lineno">  181</span>  {</div>
<div class="line"><a id="l00182" name="l00182"></a><span class="lineno">  182</span>    <a class="code hl_typedef" href="classflow_1_1log_1_1Async__file__logger.html#a10757ede565842d0faebf50bc1424610">Lock_guard</a> lock(<a class="code hl_variable" href="classflow_1_1log_1_1Async__file__logger.html#a99cd4faff109ef35720fbed9837973dc">m_throttling_mutex</a>); <span class="comment">// Careful: really_log()s may well be happening right now via m_async_worker.</span></div>
<div class="line"><a id="l00183" name="l00183"></a><span class="lineno">  183</span> </div>
<div class="line"><a id="l00184" name="l00184"></a><span class="lineno">  184</span>    <a class="code hl_define" href="log_8hpp.html#a325fdd4b5cf0be49b37d3b7b7c29070d">FLOW_LOG_INFO</a>(<span class="stringliteral">&quot;Async_file_logger [&quot;</span> &lt;&lt; <span class="keyword">this</span> &lt;&lt; <span class="stringliteral">&quot;]: Deleting.  Worker thread will flush &quot;</span></div>
<div class="line"><a id="l00185" name="l00185"></a><span class="lineno">  185</span>                  <span class="stringliteral">&quot;output if possible; then we will proceed to shut down.  Current mem-use of queued &quot;</span></div>
<div class="line"><a id="l00186" name="l00186"></a><span class="lineno">  186</span>                  <span class="stringliteral">&quot;log-requests is [&quot;</span> &lt;&lt; <a class="code hl_variable" href="classflow_1_1log_1_1Async__file__logger.html#a7cce9184c2137aa4c2d09894e1aaa7c9">m_pending_logs_sz</a> &lt;&lt; <span class="stringliteral">&quot;]; if it is large, this might take some time.&quot;</span>);</div>
<div class="line"><a id="l00187" name="l00187"></a><span class="lineno">  187</span>  }</div>
<div class="line"><a id="l00188" name="l00188"></a><span class="lineno">  188</span> </div>
<div class="line"><a id="l00189" name="l00189"></a><span class="lineno">  189</span>  <span class="comment">/* Could do this from current thread (in fact if we simply deleted the following statement, that is what would</span></div>
<div class="line"><a id="l00190" name="l00190"></a><span class="lineno">  190</span><span class="comment">   * happen); that&#39;s still non-concurrent with other calls, as Serial_file_logger requires.</span></div>
<div class="line"><a id="l00191" name="l00191"></a><span class="lineno">  191</span><span class="comment">   * However there is a subtle and important reason why the following is currently actively desired:</span></div>
<div class="line"><a id="l00192" name="l00192"></a><span class="lineno">  192</span><span class="comment">   * By post()ing it -- meaning enqueuing it -- after any log-requests (function objects with a Log_request</span></div>
<div class="line"><a id="l00193" name="l00193"></a><span class="lineno">  193</span><span class="comment">   * capture in each), and then awaiting the completion, we ensure those log requests are first serviced,</span></div>
<div class="line"><a id="l00194" name="l00194"></a><span class="lineno">  194</span><span class="comment">   * or more in English: any pending log messages are actually written to file.</span></div>
<div class="line"><a id="l00195" name="l00195"></a><span class="lineno">  195</span><span class="comment">   *</span></div>
<div class="line"><a id="l00196" name="l00196"></a><span class="lineno">  196</span><span class="comment">   * Were we to not do so, some aspects of Log_request would be leaked here; as of this writing the message and</span></div>
<div class="line"><a id="l00197" name="l00197"></a><span class="lineno">  197</span><span class="comment">   * the metadata.  (They are not RAII for reasons explained in Log_request doc header.)</span></div>
<div class="line"><a id="l00198" name="l00198"></a><span class="lineno">  198</span><span class="comment">   *</span></div>
<div class="line"><a id="l00199" name="l00199"></a><span class="lineno">  199</span><span class="comment">   * Note: If we wanted to avoid this behavior -- e.g., if huge amounts of log-requests have been queued, this</span></div>
<div class="line"><a id="l00200" name="l00200"></a><span class="lineno">  200</span><span class="comment">   * statement can very much take quite a while, and maybe we want that, or maybe we don&#39;t -- and wanted to</span></div>
<div class="line"><a id="l00201" name="l00201"></a><span class="lineno">  201</span><span class="comment">   * avoid a leak, we&#39;d need to come up with some new trick.  For the time being though by doing this flush</span></div>
<div class="line"><a id="l00202" name="l00202"></a><span class="lineno">  202</span><span class="comment">   * we both get desired functional behavior and avoid the leak. */</span></div>
<div class="line"><a id="l00203" name="l00203"></a><span class="lineno">  203</span>  <a class="code hl_variable" href="classflow_1_1log_1_1Async__file__logger.html#a2cbf044c57201ea66c2c7fa0026846eb">m_async_worker</a>.<a class="code hl_function" href="classflow_1_1async_1_1Single__thread__task__loop.html#adaf7dbd5fbd6ee7c886daabc7a6ad0ae">post</a>([<span class="keyword">this</span>]() { <a class="code hl_variable" href="classflow_1_1log_1_1Async__file__logger.html#a5c06c592797c70077fc02c98ebf231da">m_serial_logger</a>.reset(); },</div>
<div class="line"><a id="l00204" name="l00204"></a><span class="lineno">  204</span>                      Synchronicity::S_ASYNC_AND_AWAIT_CONCURRENT_COMPLETION);</div>
<div class="line"><a id="l00205" name="l00205"></a><span class="lineno">  205</span> </div>
<div class="line"><a id="l00206" name="l00206"></a><span class="lineno">  206</span>  <span class="comment">// Now thread will exit and be joined, etc.</span></div>
<div class="line"><a id="l00207" name="l00207"></a><span class="lineno">  207</span>}</div>
<div class="line"><a id="l00208" name="l00208"></a><span class="lineno">  208</span> </div>
<div class="line"><a id="l00209" name="l00209"></a><span class="lineno"><a class="line" href="classflow_1_1log_1_1Async__file__logger.html#a541843c3b49c59a70aad70d8ab984188">  209</a></span><span class="keywordtype">void</span> <a class="code hl_function" href="classflow_1_1log_1_1Async__file__logger.html#a541843c3b49c59a70aad70d8ab984188">Async_file_logger::on_rotate_signal</a>(<span class="keyword">const</span> <a class="code hl_typedef" href="namespaceflow.html#a29eaaa9d0fac4ce87d8b969222dbed09">Error_code</a>&amp; sys_err_code, <span class="keywordtype">int</span> sig_number)</div>
<div class="line"><a id="l00210" name="l00210"></a><span class="lineno">  210</span>{</div>
<div class="line"><a id="l00211" name="l00211"></a><span class="lineno">  211</span>  <span class="comment">// We are in m_async_worker thread.</span></div>
<div class="line"><a id="l00212" name="l00212"></a><span class="lineno">  212</span> </div>
<div class="line"><a id="l00213" name="l00213"></a><span class="lineno">  213</span>  <span class="keywordflow">if</span> (sys_err_code == boost::asio::error::operation_aborted)</div>
<div class="line"><a id="l00214" name="l00214"></a><span class="lineno">  214</span>  {</div>
<div class="line"><a id="l00215" name="l00215"></a><span class="lineno">  215</span>    <span class="keywordflow">return</span>; <span class="comment">// Stuff is shutting down; just get out.</span></div>
<div class="line"><a id="l00216" name="l00216"></a><span class="lineno">  216</span>  }</div>
<div class="line"><a id="l00217" name="l00217"></a><span class="lineno">  217</span>  <span class="comment">// else</span></div>
<div class="line"><a id="l00218" name="l00218"></a><span class="lineno">  218</span> </div>
<div class="line"><a id="l00219" name="l00219"></a><span class="lineno">  219</span>  <a class="code hl_define" href="log_8hpp.html#a325fdd4b5cf0be49b37d3b7b7c29070d">FLOW_LOG_INFO</a>(<span class="stringliteral">&quot;Async_file_logger [&quot;</span> &lt;&lt; <span class="keyword">this</span> &lt;&lt; <span class="stringliteral">&quot;]: &quot;</span></div>
<div class="line"><a id="l00220" name="l00220"></a><span class="lineno">  220</span>                <span class="stringliteral">&quot;Internal log-rotate handler executed with signal number [&quot;</span> &lt;&lt; sig_number &lt;&lt; <span class="stringliteral">&quot;].&quot;</span>);</div>
<div class="line"><a id="l00221" name="l00221"></a><span class="lineno">  221</span> </div>
<div class="line"><a id="l00222" name="l00222"></a><span class="lineno">  222</span>  <span class="keywordflow">if</span> (sys_err_code)</div>
<div class="line"><a id="l00223" name="l00223"></a><span class="lineno">  223</span>  {</div>
<div class="line"><a id="l00224" name="l00224"></a><span class="lineno">  224</span>    <span class="comment">// This is odd, but there&#39;s no need to freak out about anything else.  Just log and get out.</span></div>
<div class="line"><a id="l00225" name="l00225"></a><span class="lineno">  225</span>    <a class="code hl_define" href="error_2error_8hpp.html#a019ee6e90802e444572dd78d312d6e23">FLOW_ERROR_SYS_ERROR_LOG_WARNING</a>();</div>
<div class="line"><a id="l00226" name="l00226"></a><span class="lineno">  226</span>    <a class="code hl_define" href="log_8hpp.html#a626c7dc4d3b4dc0b32a8aac8624d66bc">FLOW_LOG_WARNING</a>(<span class="stringliteral">&quot;Async_file_logger [&quot;</span> &lt;&lt; <span class="keyword">this</span> &lt;&lt; <span class="stringliteral">&quot;]: &quot;</span></div>
<div class="line"><a id="l00227" name="l00227"></a><span class="lineno">  227</span>                     <span class="stringliteral">&quot;Internal signal handler executed with an error indicator.  Strange!  &quot;</span></div>
<div class="line"><a id="l00228" name="l00228"></a><span class="lineno">  228</span>                     <span class="stringliteral">&quot;Ignoring and continuing other operation.&quot;</span>);</div>
<div class="line"><a id="l00229" name="l00229"></a><span class="lineno">  229</span>  }</div>
<div class="line"><a id="l00230" name="l00230"></a><span class="lineno">  230</span>  <span class="keywordflow">else</span></div>
<div class="line"><a id="l00231" name="l00231"></a><span class="lineno">  231</span>  {</div>
<div class="line"><a id="l00232" name="l00232"></a><span class="lineno">  232</span>    <a class="code hl_variable" href="classflow_1_1log_1_1Async__file__logger.html#a5c06c592797c70077fc02c98ebf231da">m_serial_logger</a>-&gt;log_flush_and_reopen();</div>
<div class="line"><a id="l00233" name="l00233"></a><span class="lineno">  233</span>  }</div>
<div class="line"><a id="l00234" name="l00234"></a><span class="lineno">  234</span> </div>
<div class="line"><a id="l00235" name="l00235"></a><span class="lineno">  235</span>  <span class="comment">// Wait for it again, or else a rotation would only occur on the first signal but not thereafter.</span></div>
<div class="line"><a id="l00236" name="l00236"></a><span class="lineno">  236</span>  <a class="code hl_variable" href="classflow_1_1log_1_1Async__file__logger.html#a7192ad2ad8de3014dba6805cd60d5166">m_signal_set</a>.async_wait([<span class="keyword">this</span>](<span class="keyword">const</span> <a class="code hl_typedef" href="namespaceflow.html#a29eaaa9d0fac4ce87d8b969222dbed09">Error_code</a>&amp; sys_err_code, <span class="keywordtype">int</span> sig_number)</div>
<div class="line"><a id="l00237" name="l00237"></a><span class="lineno">  237</span>  {</div>
<div class="line"><a id="l00238" name="l00238"></a><span class="lineno">  238</span>    <a class="code hl_function" href="classflow_1_1log_1_1Async__file__logger.html#a541843c3b49c59a70aad70d8ab984188">on_rotate_signal</a>(sys_err_code, sig_number);</div>
<div class="line"><a id="l00239" name="l00239"></a><span class="lineno">  239</span>  });</div>
<div class="line"><a id="l00240" name="l00240"></a><span class="lineno">  240</span>} <span class="comment">// Async_file_logger::on_rotate_signal()</span></div>
<div class="line"><a id="l00241" name="l00241"></a><span class="lineno">  241</span> </div>
<div class="line"><a id="l00242" name="l00242"></a><span class="lineno"><a class="line" href="classflow_1_1log_1_1Async__file__logger.html#aa557c0f55c1044161acc8fb54c115a3e">  242</a></span><span class="keywordtype">void</span> <a class="code hl_function" href="classflow_1_1log_1_1Async__file__logger.html#aa557c0f55c1044161acc8fb54c115a3e">Async_file_logger::do_log</a>(<a class="code hl_struct" href="structflow_1_1log_1_1Msg__metadata.html">Msg_metadata</a>* metadata, <a class="code hl_typedef" href="namespaceflow_1_1util.html#ae4dc52186797094b3040379ff19124c9">util::String_view</a> msg) <span class="comment">// Virtual.</span></div>
<div class="line"><a id="l00243" name="l00243"></a><span class="lineno">  243</span>{</div>
<div class="line"><a id="l00244" name="l00244"></a><span class="lineno">  244</span>  <span class="keyword">using </span><a class="code hl_typedef" href="namespaceflow_1_1util.html#ae4dc52186797094b3040379ff19124c9">util::String_view</a>;</div>
<div class="line"><a id="l00245" name="l00245"></a><span class="lineno">  245</span>  <span class="keyword">using </span>std::memcpy;</div>
<div class="line"><a id="l00246" name="l00246"></a><span class="lineno">  246</span> </div>
<div class="line"><a id="l00247" name="l00247"></a><span class="lineno">  247</span>  assert(metadata);</div>
<div class="line"><a id="l00248" name="l00248"></a><span class="lineno">  248</span> </div>
<div class="line"><a id="l00249" name="l00249"></a><span class="lineno">  249</span>  <span class="comment">/* Our essential task is to push the log-request onto the m_async_worker queue; the code for processing</span></div>
<div class="line"><a id="l00250" name="l00250"></a><span class="lineno">  250</span><span class="comment">   * that log-request, once the queue gets to it in that worker thread, is called really_log() and is in here too.</span></div>
<div class="line"><a id="l00251" name="l00251"></a><span class="lineno">  251</span><span class="comment">   *</span></div>
<div class="line"><a id="l00252" name="l00252"></a><span class="lineno">  252</span><span class="comment">   * Key points about how the asynchronicity/logging/queueing works: We aim to return synchronously ASAP and leave the</span></div>
<div class="line"><a id="l00253" name="l00253"></a><span class="lineno">  253</span><span class="comment">   * potentially blocking (like if hard drive has to turn on from sleep) I/O ops to the worker thread asynchronously.</span></div>
<div class="line"><a id="l00254" name="l00254"></a><span class="lineno">  254</span><span class="comment">   * There are 2 pieces of data, *metadata and `msg`, to deal with, both of which essentially must be available when</span></div>
<div class="line"><a id="l00255" name="l00255"></a><span class="lineno">  255</span><span class="comment">   * we in fact write to file via m_serial_logger.  By contract of do_log() and logs_asynchronously()==true:</span></div>
<div class="line"><a id="l00256" name="l00256"></a><span class="lineno">  256</span><span class="comment">   *   - We are to NOT copy *metadata; and therefore we are to `delete metadata` when done with it; i.e., after</span></div>
<div class="line"><a id="l00257" name="l00257"></a><span class="lineno">  257</span><span class="comment">   *     m_serial_logger-&gt;do_log() returns having written to file-system.</span></div>
<div class="line"><a id="l00258" name="l00258"></a><span class="lineno">  258</span><span class="comment">   *   - We MUST copy `msg` so we can use it asynchronously; we are to therefore free the copy ourselves once</span></div>
<div class="line"><a id="l00259" name="l00259"></a><span class="lineno">  259</span><span class="comment">   *     m_serial_logger-&gt;do_log() returns.  (In reality this is all because `msg` is a shared thread-lcl thing that is</span></div>
<div class="line"><a id="l00260" name="l00260"></a><span class="lineno">  260</span><span class="comment">   *     reused in every subsequent and preceding FLOW_LOG_WARNING/etc. invocation in this thread.  We technically don&#39;t</span></div>
<div class="line"><a id="l00261" name="l00261"></a><span class="lineno">  261</span><span class="comment">   *     know or care about that reality in here; only the *result* wherein we cannot use `msg` after do_log()</span></div>
<div class="line"><a id="l00262" name="l00262"></a><span class="lineno">  262</span><span class="comment">   *     synchronously returns.)</span></div>
<div class="line"><a id="l00263" name="l00263"></a><span class="lineno">  263</span><span class="comment">   *</span></div>
<div class="line"><a id="l00264" name="l00264"></a><span class="lineno">  264</span><span class="comment">   * Here&#39;s the Log_request encapsulating that stuff.  See Log_request doc header for some nitty-gritty details. */</span></div>
<div class="line"><a id="l00265" name="l00265"></a><span class="lineno">  265</span>  <span class="keyword">const</span> <span class="keyword">auto</span> msg_sz = msg.size();</div>
<div class="line"><a id="l00266" name="l00266"></a><span class="lineno">  266</span>  <a class="code hl_struct" href="structflow_1_1log_1_1Async__file__logger_1_1Log__request.html">Log_request</a> log_request{ <span class="keyword">new</span> <span class="keywordtype">char</span>[msg_sz], msg_sz, metadata,</div>
<div class="line"><a id="l00267" name="l00267"></a><span class="lineno">  267</span>                           <span class="keyword">false</span> }; <span class="comment">// We can&#39;t know m_throttling_begins yet.</span></div>
<div class="line"><a id="l00268" name="l00268"></a><span class="lineno">  268</span>  memcpy(log_request.m_msg_copy, msg.data(), msg_sz);</div>
<div class="line"><a id="l00269" name="l00269"></a><span class="lineno">  269</span> </div>
<div class="line"><a id="l00270" name="l00270"></a><span class="lineno">  270</span>  <span class="comment">/* Before enqueuing that stuff, though, let&#39;s tally up the stats and otherwise proceed with the throttling algorithm.</span></div>
<div class="line"><a id="l00271" name="l00271"></a><span class="lineno">  271</span><span class="comment">   * Please see Impl section of class doc header for detailed discussion.  Then come back here.</span></div>
<div class="line"><a id="l00272" name="l00272"></a><span class="lineno">  272</span><span class="comment">   * We rely on the background in that discussion frequently.</span></div>
<div class="line"><a id="l00273" name="l00273"></a><span class="lineno">  273</span><span class="comment">   *</span></div>
<div class="line"><a id="l00274" name="l00274"></a><span class="lineno">  274</span><span class="comment">   * Reminder: We should be careful to minimize computation in this section (but nowhere near as important to do so</span></div>
<div class="line"><a id="l00275" name="l00275"></a><span class="lineno">  275</span><span class="comment">   * compared to should_log()).  Similarly keep the locked section as small as possible. */</span></div>
<div class="line"><a id="l00276" name="l00276"></a><span class="lineno">  276</span> </div>
<div class="line"><a id="l00277" name="l00277"></a><span class="lineno">  277</span>  <span class="keyword">using </span>logs_sz_t = <span class="keyword">decltype</span>(<a class="code hl_variable" href="classflow_1_1log_1_1Async__file__logger.html#a7cce9184c2137aa4c2d09894e1aaa7c9">m_pending_logs_sz</a>);</div>
<div class="line"><a id="l00278" name="l00278"></a><span class="lineno">  278</span>  <span class="keyword">const</span> <span class="keyword">auto</span> logs_sz = <a class="code hl_function" href="classflow_1_1log_1_1Async__file__logger.html#a6d74d81cb726a30f33f4fc106e3be5b6">mem_cost</a>(log_request);</div>
<div class="line"><a id="l00279" name="l00279"></a><span class="lineno">  279</span>  <span class="keyword">auto</span>&amp; throttling_begins = log_request.m_throttling_begins;</div>
<div class="line"><a id="l00280" name="l00280"></a><span class="lineno">  280</span>  logs_sz_t limit;</div>
<div class="line"><a id="l00281" name="l00281"></a><span class="lineno">  281</span>  logs_sz_t pending_logs_sz; <span class="comment">// For logging.</span></div>
<div class="line"><a id="l00282" name="l00282"></a><span class="lineno">  282</span>  logs_sz_t prev_pending_logs_sz;</div>
<div class="line"><a id="l00283" name="l00283"></a><span class="lineno">  283</span>  {</div>
<div class="line"><a id="l00284" name="l00284"></a><span class="lineno">  284</span>    <a class="code hl_typedef" href="classflow_1_1log_1_1Async__file__logger.html#a10757ede565842d0faebf50bc1424610">Lock_guard</a> lock(<a class="code hl_variable" href="classflow_1_1log_1_1Async__file__logger.html#a99cd4faff109ef35720fbed9837973dc">m_throttling_mutex</a>);</div>
<div class="line"><a id="l00285" name="l00285"></a><span class="lineno">  285</span>    limit = <span class="keyword">static_cast&lt;</span>logs_sz_t<span class="keyword">&gt;</span>(<a class="code hl_variable" href="classflow_1_1log_1_1Async__file__logger.html#aa3d544ab96299a8c2b53b7be485d1a6e">m_throttling_cfg</a>.<a class="code hl_variable" href="structflow_1_1log_1_1Async__file__logger_1_1Throttling__cfg.html#a7a30343e388c65594d06baed25b1aaa9">m_hi_limit</a>);</div>
<div class="line"><a id="l00286" name="l00286"></a><span class="lineno">  286</span>    prev_pending_logs_sz = <a class="code hl_variable" href="classflow_1_1log_1_1Async__file__logger.html#a7cce9184c2137aa4c2d09894e1aaa7c9">m_pending_logs_sz</a>;</div>
<div class="line"><a id="l00287" name="l00287"></a><span class="lineno">  287</span>    pending_logs_sz = (<a class="code hl_variable" href="classflow_1_1log_1_1Async__file__logger.html#a7cce9184c2137aa4c2d09894e1aaa7c9">m_pending_logs_sz</a> += logs_sz);</div>
<div class="line"><a id="l00288" name="l00288"></a><span class="lineno">  288</span>    <span class="comment">/* Minor/subtlety: We could also remove the m_throttling_now check here and instead use</span></div>
<div class="line"><a id="l00289" name="l00289"></a><span class="lineno">  289</span><span class="comment">     * `throttling_begins = (m_throttling_now.exchange() == false)` in { body }.  However we already had to lock</span></div>
<div class="line"><a id="l00290" name="l00290"></a><span class="lineno">  290</span><span class="comment">     * mutex for ~unrelated reasons, and therefore m_throttling_now cannot change at the moment; so we</span></div>
<div class="line"><a id="l00291" name="l00291"></a><span class="lineno">  291</span><span class="comment">     * might as well gate the integer comparisons on its value -- which rarely changes -- and only assign</span></div>
<div class="line"><a id="l00292" name="l00292"></a><span class="lineno">  292</span><span class="comment">     * it, if its value would in fact change. */</span></div>
<div class="line"><a id="l00293" name="l00293"></a><span class="lineno">  293</span>    <span class="keywordflow">if</span> ((!<a class="code hl_variable" href="classflow_1_1log_1_1Async__file__logger.html#aa13ef30bc2d66758c29c31dc76a130aa">m_throttling_now</a>.load(std::memory_order_relaxed))</div>
<div class="line"><a id="l00294" name="l00294"></a><span class="lineno">  294</span>        &amp;&amp; (pending_logs_sz &gt;= limit) &amp;&amp; (prev_pending_logs_sz &lt; limit))</div>
<div class="line"><a id="l00295" name="l00295"></a><span class="lineno">  295</span>    {</div>
<div class="line"><a id="l00296" name="l00296"></a><span class="lineno">  296</span>      <a class="code hl_variable" href="classflow_1_1log_1_1Async__file__logger.html#aa13ef30bc2d66758c29c31dc76a130aa">m_throttling_now</a>.store(<span class="keyword">true</span>, std::memory_order_relaxed);</div>
<div class="line"><a id="l00297" name="l00297"></a><span class="lineno">  297</span>      throttling_begins = <span class="keyword">true</span>;</div>
<div class="line"><a id="l00298" name="l00298"></a><span class="lineno">  298</span>    }</div>
<div class="line"><a id="l00299" name="l00299"></a><span class="lineno">  299</span>  }</div>
<div class="line"><a id="l00300" name="l00300"></a><span class="lineno">  300</span>  <span class="keywordflow">if</span> (throttling_begins)</div>
<div class="line"><a id="l00301" name="l00301"></a><span class="lineno">  301</span>  {</div>
<div class="line"><a id="l00302" name="l00302"></a><span class="lineno">  302</span>    <span class="comment">/* Log about it in the backup Logger (Logger-about-logging).</span></div>
<div class="line"><a id="l00303" name="l00303"></a><span class="lineno">  303</span><span class="comment">     * When throttling feature is disabled: arguably it is still worthy of being a WARNING: it is in fact warning</span></div>
<div class="line"><a id="l00304" name="l00304"></a><span class="lineno">  304</span><span class="comment">     * about a probably-bad situation (normal mem-use is roughly 0); and it is definitely useful information that</span></div>
<div class="line"><a id="l00305" name="l00305"></a><span class="lineno">  305</span><span class="comment">     * might cause end user to enable throttling.  However, subjectively, if they haven&#39;t enabled throttling then</span></div>
<div class="line"><a id="l00306" name="l00306"></a><span class="lineno">  306</span><span class="comment">     * being faced with a WARNING (error message) is arguably excessive.  Hence log it as INFO in that case.</span></div>
<div class="line"><a id="l00307" name="l00307"></a><span class="lineno">  307</span><span class="comment">     * (If they don&#39;t want these messages at all, they can always set m_hi_limit to a terabyte or something.)</span></div>
<div class="line"><a id="l00308" name="l00308"></a><span class="lineno">  308</span><span class="comment">     * Note: There&#39;s a similar statement inside really_log(). */</span></div>
<div class="line"><a id="l00309" name="l00309"></a><span class="lineno">  309</span>    <span class="keyword">const</span> <span class="keywordtype">bool</span> active = <a class="code hl_variable" href="classflow_1_1log_1_1Async__file__logger.html#a5bbad8cea27134844e73daff014cc82a">m_throttling_active</a>.load(std::memory_order_relaxed);</div>
<div class="line"><a id="l00310" name="l00310"></a><span class="lineno">  310</span>    <a class="code hl_define" href="log_8hpp.html#a692bbadd8b5c3e9cef7a0bbea1915e66">FLOW_LOG_WITH_CHECKING</a></div>
<div class="line"><a id="l00311" name="l00311"></a><span class="lineno">  311</span>      (active ? <a class="code hl_enumvalue" href="namespaceflow_1_1log.html#a5c602384e6fe9d7642740ac2fae4ad04a4aee6034ce9dbc2b5c36f27c80abe021">Sev::S_WARNING</a> : <a class="code hl_enumvalue" href="namespaceflow_1_1log.html#a5c602384e6fe9d7642740ac2fae4ad04ac238793326fae17afcc849e96b96e8e7">Sev::S_INFO</a>,</div>
<div class="line"><a id="l00312" name="l00312"></a><span class="lineno">  312</span>       <span class="stringliteral">&quot;Async_file_logger [&quot;</span> &lt;&lt; <span class="keyword">this</span> &lt;&lt; <span class="stringliteral">&quot;]: &quot;</span></div>
<div class="line"><a id="l00313" name="l00313"></a><span class="lineno">  313</span>         <span class="stringliteral">&quot;do_log() throttling algorithm: a message reached hi_limit; next message-to-be =&gt; likely dropped, &quot;</span></div>
<div class="line"><a id="l00314" name="l00314"></a><span class="lineno">  314</span>         <span class="stringliteral">&quot;if feature active.  Config: hi_limit [&quot;</span> &lt;&lt; limit &lt;&lt; <span class="stringliteral">&quot;].  &quot;</span></div>
<div class="line"><a id="l00315" name="l00315"></a><span class="lineno">  315</span>         <span class="stringliteral">&quot;Mem-use = [&quot;</span> &lt;&lt; prev_pending_logs_sz &lt;&lt; <span class="stringliteral">&quot;] =&gt; [&quot;</span> &lt;&lt; pending_logs_sz &lt;&lt; <span class="stringliteral">&quot;]; &quot;</span></div>
<div class="line"><a id="l00316" name="l00316"></a><span class="lineno">  316</span>         <span class="stringliteral">&quot;throttling? = 1 (see above); throttling feature active? = [&quot;</span> &lt;&lt; active &lt;&lt; <span class="stringliteral">&quot;].  &quot;</span></div>
<div class="line"><a id="l00317" name="l00317"></a><span class="lineno">  317</span>         <span class="stringliteral">&quot;Reminder: `throttling?` shall only be used if `throttling feature active?` is 1.  &quot;</span></div>
<div class="line"><a id="l00318" name="l00318"></a><span class="lineno">  318</span>         <span class="stringliteral">&quot;Limit-triggering message&#39;s contents follow: [&quot;</span> &lt;&lt; msg &lt;&lt; <span class="stringliteral">&quot;].&quot;</span>);</div>
<div class="line"><a id="l00319" name="l00319"></a><span class="lineno">  319</span>  }</div>
<div class="line"><a id="l00320" name="l00320"></a><span class="lineno">  320</span><span class="preprocessor">#if 0 </span><span class="comment">// Obv change to `if 1` if debugging + want to see it.  Could just use TRACE but avoiding should_log() cost.</span></div>
<div class="line"><a id="l00321" name="l00321"></a><span class="lineno">  321</span>  <span class="keywordflow">else</span></div>
<div class="line"><a id="l00322" name="l00322"></a><span class="lineno">  322</span>  {</div>
<div class="line"><a id="l00323" name="l00323"></a><span class="lineno">  323</span>    <a class="code hl_define" href="log_8hpp.html#a325fdd4b5cf0be49b37d3b7b7c29070d">FLOW_LOG_INFO</a>(<span class="stringliteral">&quot;Async_file_logger [&quot;</span> &lt;&lt; <span class="keyword">this</span> &lt;&lt; <span class="stringliteral">&quot;]: &quot;</span></div>
<div class="line"><a id="l00324" name="l00324"></a><span class="lineno">  324</span>                  <span class="stringliteral">&quot;do_log() throttling algorithm: a message was processed; situation (reminder: beware concurrency): &quot;</span></div>
<div class="line"><a id="l00325" name="l00325"></a><span class="lineno">  325</span>                  <span class="stringliteral">&quot;Config: hi_limit [&quot;</span> &lt;&lt; limit &lt;&lt; <span class="stringliteral">&quot;].  &quot;</span></div>
<div class="line"><a id="l00326" name="l00326"></a><span class="lineno">  326</span>                  <span class="stringliteral">&quot;Mem-use = [&quot;</span> &lt;&lt; prev_pending_logs_sz &lt;&lt; <span class="stringliteral">&quot;] =&gt; [&quot;</span> &lt;&lt; pending_logs_sz &lt;&lt; <span class="stringliteral">&quot;]; &quot;</span></div>
<div class="line"><a id="l00327" name="l00327"></a><span class="lineno">  327</span>                  <span class="stringliteral">&quot;throttling feature active? = [&quot;</span> &lt;&lt; <a class="code hl_variable" href="classflow_1_1log_1_1Async__file__logger.html#a5bbad8cea27134844e73daff014cc82a">m_throttling_active</a>.load(std::memory_order_relaxed) &lt;&lt; <span class="stringliteral">&quot;].  &quot;</span></div>
<div class="line"><a id="l00328" name="l00328"></a><span class="lineno">  328</span>                  <span class="stringliteral">&quot;Message&#39;s contents follow: [&quot;</span> &lt;&lt; msg &lt;&lt; <span class="stringliteral">&quot;].&quot;</span>);</div>
<div class="line"><a id="l00329" name="l00329"></a><span class="lineno">  329</span>  }</div>
<div class="line"><a id="l00330" name="l00330"></a><span class="lineno">  330</span><span class="preprocessor">#endif</span></div>
<div class="line"><a id="l00331" name="l00331"></a><span class="lineno">  331</span> </div>
<div class="line"><a id="l00332" name="l00332"></a><span class="lineno">  332</span>  <span class="comment">/* Done! State updated, and throttling_begins determined for really_log().</span></div>
<div class="line"><a id="l00333" name="l00333"></a><span class="lineno">  333</span><span class="comment">   *</span></div>
<div class="line"><a id="l00334" name="l00334"></a><span class="lineno">  334</span><span class="comment">   * Now for the enqueueing of the log-request.  This is what will execute in m_async_worker, when it&#39;s its turn. */</span></div>
<div class="line"><a id="l00335" name="l00335"></a><span class="lineno">  335</span> </div>
<div class="line"><a id="l00336" name="l00336"></a><span class="lineno">  336</span>  <span class="keyword">auto</span> really_log = [<span class="keyword">this</span>, log_request = std::move(log_request)]() <span class="keyword">mutable</span></div>
<div class="line"><a id="l00337" name="l00337"></a><span class="lineno">  337</span>  {</div>
<div class="line"><a id="l00338" name="l00338"></a><span class="lineno">  338</span>    <span class="keyword">const</span> <span class="keyword">auto</span> metadata = log_request.m_metadata;</div>
<div class="line"><a id="l00339" name="l00339"></a><span class="lineno">  339</span>    <span class="keyword">const</span> <a class="code hl_typedef" href="namespaceflow_1_1util.html#ae4dc52186797094b3040379ff19124c9">String_view</a> msg{log_request.m_msg_copy, log_request.m_msg_size};</div>
<div class="line"><a id="l00340" name="l00340"></a><span class="lineno">  340</span> </div>
<div class="line"><a id="l00341" name="l00341"></a><span class="lineno">  341</span>    <span class="comment">/* Throttling: do, essentially, the opposite of what do_log() did when issuing the log-request.</span></div>
<div class="line"><a id="l00342" name="l00342"></a><span class="lineno">  342</span><span class="comment">     * Again please refer to Impl section of class doc header for reasoning about this algorithm. */</span></div>
<div class="line"><a id="l00343" name="l00343"></a><span class="lineno">  343</span> </div>
<div class="line"><a id="l00344" name="l00344"></a><span class="lineno">  344</span>    <span class="keyword">const</span> <span class="keyword">auto</span> logs_sz = <a class="code hl_function" href="classflow_1_1log_1_1Async__file__logger.html#a6d74d81cb726a30f33f4fc106e3be5b6">mem_cost</a>(log_request);</div>
<div class="line"><a id="l00345" name="l00345"></a><span class="lineno">  345</span>    <span class="comment">// @todo ^-- Maybe instead save this in Log_request?  Trade-off is RAM vs cycles (currently favoring RAM).</span></div>
<div class="line"><a id="l00346" name="l00346"></a><span class="lineno">  346</span>    <span class="keywordtype">bool</span> throttling_ends = <span class="keyword">false</span>;</div>
<div class="line"><a id="l00347" name="l00347"></a><span class="lineno">  347</span>    logs_sz_t limit; <span class="comment">// For logging.</span></div>
<div class="line"><a id="l00348" name="l00348"></a><span class="lineno">  348</span>    logs_sz_t pending_logs_sz; <span class="comment">// For logging.</span></div>
<div class="line"><a id="l00349" name="l00349"></a><span class="lineno">  349</span>    logs_sz_t prev_pending_logs_sz;</div>
<div class="line"><a id="l00350" name="l00350"></a><span class="lineno">  350</span>    {</div>
<div class="line"><a id="l00351" name="l00351"></a><span class="lineno">  351</span>      <a class="code hl_typedef" href="classflow_1_1log_1_1Async__file__logger.html#a10757ede565842d0faebf50bc1424610">Lock_guard</a> lock(<a class="code hl_variable" href="classflow_1_1log_1_1Async__file__logger.html#a99cd4faff109ef35720fbed9837973dc">m_throttling_mutex</a>);</div>
<div class="line"><a id="l00352" name="l00352"></a><span class="lineno">  352</span>      limit = <a class="code hl_variable" href="classflow_1_1log_1_1Async__file__logger.html#aa3d544ab96299a8c2b53b7be485d1a6e">m_throttling_cfg</a>.<a class="code hl_variable" href="structflow_1_1log_1_1Async__file__logger_1_1Throttling__cfg.html#a7a30343e388c65594d06baed25b1aaa9">m_hi_limit</a>; <span class="comment">// Just for logging in this case.</span></div>
<div class="line"><a id="l00353" name="l00353"></a><span class="lineno">  353</span>      prev_pending_logs_sz = <a class="code hl_variable" href="classflow_1_1log_1_1Async__file__logger.html#a7cce9184c2137aa4c2d09894e1aaa7c9">m_pending_logs_sz</a>;</div>
<div class="line"><a id="l00354" name="l00354"></a><span class="lineno">  354</span>      assert((prev_pending_logs_sz &gt;= logs_sz) &amp;&amp; <span class="stringliteral">&quot;Bug?  really_log() has no matching do_log()?&quot;</span>);</div>
<div class="line"><a id="l00355" name="l00355"></a><span class="lineno">  355</span>      pending_logs_sz = (<a class="code hl_variable" href="classflow_1_1log_1_1Async__file__logger.html#a7cce9184c2137aa4c2d09894e1aaa7c9">m_pending_logs_sz</a> -= logs_sz);</div>
<div class="line"><a id="l00356" name="l00356"></a><span class="lineno">  356</span>      <span class="comment">/* Minor/subtlety: Versus the do_log() equivalent above, it looks more economical to check pending_logs_sz first,</span></div>
<div class="line"><a id="l00357" name="l00357"></a><span class="lineno">  357</span><span class="comment">       * since it just compares one value to 0 in this case (as opposed to 2 values and &lt; and &gt;=), and then both set</span></div>
<div class="line"><a id="l00358" name="l00358"></a><span class="lineno">  358</span><span class="comment">       * m_throttling_now and check its preceding value in one op. */</span></div>
<div class="line"><a id="l00359" name="l00359"></a><span class="lineno">  359</span>      <span class="keywordflow">if</span> (pending_logs_sz == 0)</div>
<div class="line"><a id="l00360" name="l00360"></a><span class="lineno">  360</span>      {</div>
<div class="line"><a id="l00361" name="l00361"></a><span class="lineno">  361</span>        <span class="comment">// m_throttling_now should be false; but detect whether this is the change-over from true as opposed to no-op.</span></div>
<div class="line"><a id="l00362" name="l00362"></a><span class="lineno">  362</span>        throttling_ends = (<a class="code hl_variable" href="classflow_1_1log_1_1Async__file__logger.html#aa13ef30bc2d66758c29c31dc76a130aa">m_throttling_now</a>.exchange(<span class="keyword">false</span>, std::memory_order_relaxed) == <span class="keyword">true</span>);</div>
<div class="line"><a id="l00363" name="l00363"></a><span class="lineno">  363</span>      }</div>
<div class="line"><a id="l00364" name="l00364"></a><span class="lineno">  364</span>    }</div>
<div class="line"><a id="l00365" name="l00365"></a><span class="lineno">  365</span> </div>
<div class="line"><a id="l00366" name="l00366"></a><span class="lineno">  366</span>    <span class="keywordflow">if</span> (throttling_ends)</div>
<div class="line"><a id="l00367" name="l00367"></a><span class="lineno">  367</span>    {</div>
<div class="line"><a id="l00368" name="l00368"></a><span class="lineno">  368</span>      <span class="comment">// Log about it in the backup Logger (Logger-about-logging).</span></div>
<div class="line"><a id="l00369" name="l00369"></a><span class="lineno">  369</span>      <a class="code hl_define" href="log_8hpp.html#a325fdd4b5cf0be49b37d3b7b7c29070d">FLOW_LOG_INFO</a>(<span class="stringliteral">&quot;Async_file_logger [&quot;</span> &lt;&lt; <span class="keyword">this</span> &lt;&lt; <span class="stringliteral">&quot;]: last pending message was logged; &quot;</span></div>
<div class="line"><a id="l00370" name="l00370"></a><span class="lineno">  370</span>                    <span class="stringliteral">&quot;next message-to-be =&gt; likely first one to *not* be dropped, if throttling feature active.  &quot;</span></div>
<div class="line"><a id="l00371" name="l00371"></a><span class="lineno">  371</span>                    <span class="stringliteral">&quot;Config: hi_limit [&quot;</span> &lt;&lt; limit &lt;&lt; <span class="stringliteral">&quot;].  &quot;</span></div>
<div class="line"><a id="l00372" name="l00372"></a><span class="lineno">  372</span>                    <span class="stringliteral">&quot;Mem-use = [&quot;</span> &lt;&lt; prev_pending_logs_sz &lt;&lt; <span class="stringliteral">&quot;] =&gt; [&quot;</span> &lt;&lt; pending_logs_sz &lt;&lt; <span class="stringliteral">&quot;]; &quot;</span></div>
<div class="line"><a id="l00373" name="l00373"></a><span class="lineno">  373</span>                    <span class="stringliteral">&quot;throttling? = 0 (see above); &quot;</span></div>
<div class="line"><a id="l00374" name="l00374"></a><span class="lineno">  374</span>                    <span class="stringliteral">&quot;throttling feature active? = [&quot;</span> &lt;&lt; <a class="code hl_variable" href="classflow_1_1log_1_1Async__file__logger.html#a5bbad8cea27134844e73daff014cc82a">m_throttling_active</a>.load(std::memory_order_relaxed) &lt;&lt; <span class="stringliteral">&quot;].  &quot;</span></div>
<div class="line"><a id="l00375" name="l00375"></a><span class="lineno">  375</span>                    <span class="stringliteral">&quot;Reminder: `throttling?` shall only be used if `throttling feature active?` is 1.  &quot;</span></div>
<div class="line"><a id="l00376" name="l00376"></a><span class="lineno">  376</span>                    <span class="stringliteral">&quot;Queue-clearing message&#39;s contents follow: [&quot;</span> &lt;&lt; msg &lt;&lt; <span class="stringliteral">&quot;].&quot;</span>);</div>
<div class="line"><a id="l00377" name="l00377"></a><span class="lineno">  377</span> </div>
<div class="line"><a id="l00378" name="l00378"></a><span class="lineno">  378</span>      <span class="comment">// Log about it in file itself.  (Performance in this block is not of huge import; this is a fairly rare event.)</span></div>
<div class="line"><a id="l00379" name="l00379"></a><span class="lineno">  379</span>      <a class="code hl_define" href="log_8hpp.html#ae4b5d4fdd2eb052615620879dd74af95">FLOW_LOG_SET_CONTEXT</a>(<a class="code hl_variable" href="classflow_1_1log_1_1Async__file__logger.html#a5c06c592797c70077fc02c98ebf231da">m_serial_logger</a>.get(), this-&gt;get_log_component());</div>
<div class="line"><a id="l00380" name="l00380"></a><span class="lineno">  380</span> </div>
<div class="line"><a id="l00381" name="l00381"></a><span class="lineno">  381</span>      <a class="code hl_define" href="log_8hpp.html#a325fdd4b5cf0be49b37d3b7b7c29070d">FLOW_LOG_INFO</a>(<span class="stringliteral">&quot;Async_file_logger [&quot;</span> &lt;&lt; <span class="keyword">this</span> &lt;&lt; <span class="stringliteral">&quot;]: &quot;</span></div>
<div class="line"><a id="l00382" name="l00382"></a><span class="lineno">  382</span>                    <span class="stringliteral">&quot;really_log() throttling algorithm: last pending message was logged; &quot;</span></div>
<div class="line"><a id="l00383" name="l00383"></a><span class="lineno">  383</span>                    <span class="stringliteral">&quot;next message-to-be =&gt; likely first one to *not* be dropped, if throttling feature active.  &quot;</span></div>
<div class="line"><a id="l00384" name="l00384"></a><span class="lineno">  384</span>                    <span class="stringliteral">&quot;Config: hi_limit [&quot;</span> &lt;&lt; limit &lt;&lt; <span class="stringliteral">&quot;].  &quot;</span></div>
<div class="line"><a id="l00385" name="l00385"></a><span class="lineno">  385</span>                    <span class="stringliteral">&quot;Mem-use = [&quot;</span> &lt;&lt; prev_pending_logs_sz &lt;&lt; <span class="stringliteral">&quot;] =&gt; 0; &quot;</span></div>
<div class="line"><a id="l00386" name="l00386"></a><span class="lineno">  386</span>                    <span class="stringliteral">&quot;throttling feature active? = [&quot;</span> &lt;&lt; <a class="code hl_variable" href="classflow_1_1log_1_1Async__file__logger.html#a5bbad8cea27134844e73daff014cc82a">m_throttling_active</a>.load(std::memory_order_relaxed) &lt;&lt; <span class="stringliteral">&quot;].  &quot;</span></div>
<div class="line"><a id="l00387" name="l00387"></a><span class="lineno">  387</span>                    <span class="stringliteral">&quot;Queue-clearing message is the one immediately following me in file.  &quot;</span></div>
<div class="line"><a id="l00388" name="l00388"></a><span class="lineno">  388</span>                    <span class="stringliteral">&quot;Compare its time stamp to mine to see time lag due to queueing.&quot;</span>);</div>
<div class="line"><a id="l00389" name="l00389"></a><span class="lineno">  389</span>    }</div>
<div class="line"><a id="l00390" name="l00390"></a><span class="lineno">  390</span><span class="preprocessor">#if 0 </span><span class="comment">// Obv change to `if 1` if debugging + want to see it.  Could just use TRACE but avoiding should_log() cost.</span></div>
<div class="line"><a id="l00391" name="l00391"></a><span class="lineno">  391</span>    <span class="keywordflow">else</span></div>
<div class="line"><a id="l00392" name="l00392"></a><span class="lineno">  392</span>    {</div>
<div class="line"><a id="l00393" name="l00393"></a><span class="lineno">  393</span>      <a class="code hl_define" href="log_8hpp.html#a325fdd4b5cf0be49b37d3b7b7c29070d">FLOW_LOG_INFO</a>(<span class="stringliteral">&quot;Async_file_logger [&quot;</span> &lt;&lt; <span class="keyword">this</span> &lt;&lt; <span class="stringliteral">&quot;]: &quot;</span></div>
<div class="line"><a id="l00394" name="l00394"></a><span class="lineno">  394</span>                    <span class="stringliteral">&quot;really_log() throttling algorithm: a message is about to be written to file; &quot;</span></div>
<div class="line"><a id="l00395" name="l00395"></a><span class="lineno">  395</span>                    <span class="stringliteral">&quot;situation (reminder: beware concurrency): Config: hi_limit [&quot;</span> &lt;&lt; limit &lt;&lt; <span class="stringliteral">&quot;].  &quot;</span></div>
<div class="line"><a id="l00396" name="l00396"></a><span class="lineno">  396</span>                    <span class="stringliteral">&quot;Mem-use = [&quot;</span> &lt;&lt; prev_pending_logs_sz &lt;&lt; <span class="stringliteral">&quot;] =&gt; [&quot;</span> &lt;&lt; pending_logs_sz &lt;&lt; <span class="stringliteral">&quot;]; &quot;</span></div>
<div class="line"><a id="l00397" name="l00397"></a><span class="lineno">  397</span>                    <span class="stringliteral">&quot;throttling feature active? = [&quot;</span> &lt;&lt; <a class="code hl_variable" href="classflow_1_1log_1_1Async__file__logger.html#a5bbad8cea27134844e73daff014cc82a">m_throttling_active</a>.load(std::memory_order_relaxed) &lt;&lt; <span class="stringliteral">&quot;].  &quot;</span>);</div>
<div class="line"><a id="l00398" name="l00398"></a><span class="lineno">  398</span>                    <span class="stringliteral">&quot;Message&#39;s contents follow: [&quot;</span> &lt;&lt; msg &lt;&lt; <span class="stringliteral">&quot;].&quot;</span>);</div>
<div class="line"><a id="l00399" name="l00399"></a><span class="lineno">  399</span>    }</div>
<div class="line"><a id="l00400" name="l00400"></a><span class="lineno">  400</span><span class="preprocessor">#endif</span></div>
<div class="line"><a id="l00401" name="l00401"></a><span class="lineno">  401</span> </div>
<div class="line"><a id="l00402" name="l00402"></a><span class="lineno">  402</span>    <span class="comment">// We are in m_async_worker thread, as m_serial_logger requires.  Go!</span></div>
<div class="line"><a id="l00403" name="l00403"></a><span class="lineno">  403</span>    <a class="code hl_variable" href="classflow_1_1log_1_1Async__file__logger.html#a5c06c592797c70077fc02c98ebf231da">m_serial_logger</a>-&gt;do_log(metadata, msg);</div>
<div class="line"><a id="l00404" name="l00404"></a><span class="lineno">  404</span> </div>
<div class="line"><a id="l00405" name="l00405"></a><span class="lineno">  405</span>    <span class="comment">// Oh and obey throttling_begins for this log-request, if it was computed to be true in do_log().</span></div>
<div class="line"><a id="l00406" name="l00406"></a><span class="lineno">  406</span>    <span class="keywordflow">if</span> (log_request.m_throttling_begins)</div>
<div class="line"><a id="l00407" name="l00407"></a><span class="lineno">  407</span>    {</div>
<div class="line"><a id="l00408" name="l00408"></a><span class="lineno">  408</span>      <span class="comment">// Performance in this block is not of huge import; this is a fairly rare event.</span></div>
<div class="line"><a id="l00409" name="l00409"></a><span class="lineno">  409</span>      <a class="code hl_define" href="log_8hpp.html#ae4b5d4fdd2eb052615620879dd74af95">FLOW_LOG_SET_CONTEXT</a>(<a class="code hl_variable" href="classflow_1_1log_1_1Async__file__logger.html#a5c06c592797c70077fc02c98ebf231da">m_serial_logger</a>.get(), this-&gt;get_log_component());</div>
<div class="line"><a id="l00410" name="l00410"></a><span class="lineno">  410</span> </div>
<div class="line"><a id="l00411" name="l00411"></a><span class="lineno">  411</span>      <span class="comment">// Rationale w/r/t the Sev choice here: see similar `if (throttling_begins)` block above.</span></div>
<div class="line"><a id="l00412" name="l00412"></a><span class="lineno">  412</span>      <span class="keyword">const</span> <span class="keywordtype">bool</span> active = <a class="code hl_variable" href="classflow_1_1log_1_1Async__file__logger.html#a5bbad8cea27134844e73daff014cc82a">m_throttling_active</a>.load(std::memory_order_relaxed);</div>
<div class="line"><a id="l00413" name="l00413"></a><span class="lineno">  413</span>      <a class="code hl_define" href="log_8hpp.html#a692bbadd8b5c3e9cef7a0bbea1915e66">FLOW_LOG_WITH_CHECKING</a></div>
<div class="line"><a id="l00414" name="l00414"></a><span class="lineno">  414</span>        (active ? <a class="code hl_enumvalue" href="namespaceflow_1_1log.html#a5c602384e6fe9d7642740ac2fae4ad04a4aee6034ce9dbc2b5c36f27c80abe021">Sev::S_WARNING</a> : <a class="code hl_enumvalue" href="namespaceflow_1_1log.html#a5c602384e6fe9d7642740ac2fae4ad04ac238793326fae17afcc849e96b96e8e7">Sev::S_INFO</a>,</div>
<div class="line"><a id="l00415" name="l00415"></a><span class="lineno">  415</span>         <span class="stringliteral">&quot;Async_file_logger [&quot;</span> &lt;&lt; <span class="keyword">this</span> &lt;&lt; <span class="stringliteral">&quot;]: &quot;</span></div>
<div class="line"><a id="l00416" name="l00416"></a><span class="lineno">  416</span>           <span class="stringliteral">&quot;really_log() throttling algorithm: The preceding message, when its log-request was &quot;</span></div>
<div class="line"><a id="l00417" name="l00417"></a><span class="lineno">  417</span>           <span class="stringliteral">&quot;earlier enqueued, caused pending-logs RAM usage to exceed then-configured hi_limit.  &quot;</span></div>
<div class="line"><a id="l00418" name="l00418"></a><span class="lineno">  418</span>           <span class="stringliteral">&quot;If throttling feature was active, subsequent messages-to-be (log-requests) were dropped.  &quot;</span></div>
<div class="line"><a id="l00419" name="l00419"></a><span class="lineno">  419</span>           <span class="stringliteral">&quot;We only just got around to being able to log it (satisfy log-request) after all the &quot;</span></div>
<div class="line"><a id="l00420" name="l00420"></a><span class="lineno">  420</span>           <span class="stringliteral">&quot;preceding ones in FIFO order.  Nowadays: Config: hi_limit [&quot;</span> &lt;&lt; limit &lt;&lt; <span class="stringliteral">&quot;].  &quot;</span></div>
<div class="line"><a id="l00421" name="l00421"></a><span class="lineno">  421</span>           <span class="stringliteral">&quot;Mem-use = [&quot;</span> &lt;&lt; prev_pending_logs_sz &lt;&lt; <span class="stringliteral">&quot;] =&gt; [&quot;</span> &lt;&lt; pending_logs_sz &lt;&lt; <span class="stringliteral">&quot;]; &quot;</span></div>
<div class="line"><a id="l00422" name="l00422"></a><span class="lineno">  422</span>           <span class="stringliteral">&quot;throttling feature active? = [&quot;</span> &lt;&lt; active &lt;&lt; <span class="stringliteral">&quot;].  &quot;</span></div>
<div class="line"><a id="l00423" name="l00423"></a><span class="lineno">  423</span>           <span class="stringliteral">&quot;Limit-crossing (in the past) message is the one immediately preceding the current one &quot;</span></div>
<div class="line"><a id="l00424" name="l00424"></a><span class="lineno">  424</span>           <span class="stringliteral">&quot;you&#39;re reading in file.  &quot;</span></div>
<div class="line"><a id="l00425" name="l00425"></a><span class="lineno">  425</span>           <span class="stringliteral">&quot;Compare its time stamp to mine to see time lag due to queueing.&quot;</span>);</div>
<div class="line"><a id="l00426" name="l00426"></a><span class="lineno">  426</span>    } <span class="comment">// if (log_request.throttling_begins)</span></div>
<div class="line"><a id="l00427" name="l00427"></a><span class="lineno">  427</span> </div>
<div class="line"><a id="l00428" name="l00428"></a><span class="lineno">  428</span>    <span class="comment">/* Last but not least, as discussed in Log_request doc header, we must do this explicitly.</span></div>
<div class="line"><a id="l00429" name="l00429"></a><span class="lineno">  429</span><span class="comment">     * To reiterate: as of this writing, if this lambda body is not actually executed, then these will leak.</span></div>
<div class="line"><a id="l00430" name="l00430"></a><span class="lineno">  430</span><span class="comment">     * As of this writing we ensure it *is* executed, in the Async_file_logger dtor at the latest. */</span></div>
<div class="line"><a id="l00431" name="l00431"></a><span class="lineno">  431</span>    <span class="keyword">delete</span>[] log_request.m_msg_copy;</div>
<div class="line"><a id="l00432" name="l00432"></a><span class="lineno">  432</span>    <span class="keyword">delete</span> metadata;</div>
<div class="line"><a id="l00433" name="l00433"></a><span class="lineno">  433</span>  }; <span class="comment">// really_log =</span></div>
<div class="line"><a id="l00434" name="l00434"></a><span class="lineno">  434</span> </div>
<div class="line"><a id="l00435" name="l00435"></a><span class="lineno">  435</span>  <span class="comment">// Enqueue it, after whatever others are already pending (hopefully not too many; ideally none).</span></div>
<div class="line"><a id="l00436" name="l00436"></a><span class="lineno">  436</span>  <a class="code hl_variable" href="classflow_1_1log_1_1Async__file__logger.html#a2cbf044c57201ea66c2c7fa0026846eb">m_async_worker</a>.<a class="code hl_function" href="classflow_1_1async_1_1Single__thread__task__loop.html#adaf7dbd5fbd6ee7c886daabc7a6ad0ae">post</a>(std::move(really_log));</div>
<div class="line"><a id="l00437" name="l00437"></a><span class="lineno">  437</span>} <span class="comment">// Async_file_logger::do_log()</span></div>
<div class="line"><a id="l00438" name="l00438"></a><span class="lineno">  438</span> </div>
<div class="line"><a id="l00439" name="l00439"></a><span class="lineno"><a class="line" href="classflow_1_1log_1_1Async__file__logger.html#a6d74d81cb726a30f33f4fc106e3be5b6">  439</a></span><span class="keywordtype">size_t</span> <a class="code hl_function" href="classflow_1_1log_1_1Async__file__logger.html#a6d74d81cb726a30f33f4fc106e3be5b6">Async_file_logger::mem_cost</a>(<span class="keyword">const</span> <a class="code hl_struct" href="structflow_1_1log_1_1Async__file__logger_1_1Log__request.html">Log_request</a>&amp; log_request) <span class="comment">// Static.</span></div>
<div class="line"><a id="l00440" name="l00440"></a><span class="lineno">  440</span>{</div>
<div class="line"><a id="l00441" name="l00441"></a><span class="lineno">  441</span>  <span class="comment">/* We should strive to be quick here (also almost certainly we will be inlined, with full optimization anyway).</span></div>
<div class="line"><a id="l00442" name="l00442"></a><span class="lineno">  442</span><span class="comment">   * This is called in every do_log(), which can be not-infrequent; and really_log() in the background thread --</span></div>
<div class="line"><a id="l00443" name="l00443"></a><span class="lineno">  443</span><span class="comment">   * though extreme efficiency there is less important.</span></div>
<div class="line"><a id="l00444" name="l00444"></a><span class="lineno">  444</span><span class="comment">   *</span></div>
<div class="line"><a id="l00445" name="l00445"></a><span class="lineno">  445</span><span class="comment">   * This is an estimate; it need not be exact, as we use it as merely a heuristic when to throttle.  For example</span></div>
<div class="line"><a id="l00446" name="l00446"></a><span class="lineno">  446</span><span class="comment">   * personally I (ygoldfel) only vaguely understand how function&lt;&gt; stores stores a lambda and its captures.</span></div>
<div class="line"><a id="l00447" name="l00447"></a><span class="lineno">  447</span><span class="comment">   * That said it should be roughly proportional to the memory used. */</span></div>
<div class="line"><a id="l00448" name="l00448"></a><span class="lineno">  448</span> </div>
<div class="line"><a id="l00449" name="l00449"></a><span class="lineno">  449</span>  <span class="keywordflow">return</span> <span class="keyword">sizeof</span>(<a class="code hl_typedef" href="namespaceflow_1_1async.html#af35fb65bdea1a3a92929ec2c4a6a6b72">async::Task</a>) <span class="comment">// Don&#39;t forget the function object itself.  Then the captures:</span></div>
<div class="line"><a id="l00450" name="l00450"></a><span class="lineno">  450</span>         + <span class="keyword">sizeof</span>(<a class="code hl_class" href="classflow_1_1log_1_1Async__file__logger.html">Async_file_logger</a>*) <span class="comment">// `this`.</span></div>
<div class="line"><a id="l00451" name="l00451"></a><span class="lineno">  451</span>         + <span class="keyword">sizeof</span>(<a class="code hl_struct" href="structflow_1_1log_1_1Async__file__logger_1_1Log__request.html">Log_request</a>) <span class="comment">// The main capture is this.  Firstly its shallow size.</span></div>
<div class="line"><a id="l00452" name="l00452"></a><span class="lineno">  452</span>         + <a class="code hl_function" href="classflow_1_1log_1_1Async__file__logger.html#a9eff13fef045d9dd58a34d207ff6521e">deep_size</a>(log_request); <span class="comment">// And its size beyond sizeof (its members combined).</span></div>
<div class="line"><a id="l00453" name="l00453"></a><span class="lineno">  453</span> </div>
<div class="line"><a id="l00454" name="l00454"></a><span class="lineno">  454</span>  <span class="comment">// See end of deep_cost() for style/pattern notes.</span></div>
<div class="line"><a id="l00455" name="l00455"></a><span class="lineno">  455</span>} <span class="comment">// Async_file_logger::mem_cost()</span></div>
<div class="line"><a id="l00456" name="l00456"></a><span class="lineno">  456</span> </div>
<div class="line"><a id="l00457" name="l00457"></a><span class="lineno"><a class="line" href="classflow_1_1log_1_1Async__file__logger.html#a9eff13fef045d9dd58a34d207ff6521e">  457</a></span><span class="keywordtype">size_t</span> <a class="code hl_function" href="classflow_1_1log_1_1Async__file__logger.html#a9eff13fef045d9dd58a34d207ff6521e">Async_file_logger::deep_size</a>(<span class="keyword">const</span> <a class="code hl_struct" href="structflow_1_1log_1_1Async__file__logger_1_1Log__request.html">Log_request</a>&amp; val) <span class="comment">// Static.</span></div>
<div class="line"><a id="l00458" name="l00458"></a><span class="lineno">  458</span>{</div>
<div class="line"><a id="l00459" name="l00459"></a><span class="lineno">  459</span>  <span class="keyword">using </span><a class="code hl_function" href="namespaceflow_1_1log.html#a267187e63c6355704f547d794c776747">log::deep_size</a>;</div>
<div class="line"><a id="l00460" name="l00460"></a><span class="lineno">  460</span> </div>
<div class="line"><a id="l00461" name="l00461"></a><span class="lineno">  461</span>  <span class="keywordflow">return</span> val.<a class="code hl_variable" href="structflow_1_1log_1_1Async__file__logger_1_1Log__request.html#a43b7a817420a80d955e4acfd0ec10f45">m_msg_size</a> <span class="comment">// m_msg_copy = char*; we saved its pointee raw array&#39;s mem-use here.</span></div>
<div class="line"><a id="l00462" name="l00462"></a><span class="lineno">  462</span>         <span class="comment">// m_metadata is Msg_metadata*:</span></div>
<div class="line"><a id="l00463" name="l00463"></a><span class="lineno">  463</span>         + <span class="keyword">sizeof</span>(<a class="code hl_struct" href="structflow_1_1log_1_1Msg__metadata.html">Msg_metadata</a>) <span class="comment">// Msg_metadata shallow (to it) parts are non-shallow to *us* (it&#39;s in heap).</span></div>
<div class="line"><a id="l00464" name="l00464"></a><span class="lineno">  464</span>         + <a class="code hl_function" href="classflow_1_1log_1_1Async__file__logger.html#a9eff13fef045d9dd58a34d207ff6521e">deep_size</a>(*val.<a class="code hl_variable" href="structflow_1_1log_1_1Async__file__logger_1_1Log__request.html#a7215d35008420d5c3357df1b06761d64">m_metadata</a>); <span class="comment">// Msg_metadata&#39;s non-shallow mem-use (recursively implement deep_size() ptrn).</span></div>
<div class="line"><a id="l00465" name="l00465"></a><span class="lineno">  465</span> </div>
<div class="line"><a id="l00466" name="l00466"></a><span class="lineno">  466</span>  <span class="comment">/* Style/maintanability notes: At the risk of being overly formal: There&#39;s a pattern in play here + in mem_cost():</span></div>
<div class="line"><a id="l00467" name="l00467"></a><span class="lineno">  467</span><span class="comment">   * The total-size of aggregate object `X x` is sizeof(X) + D, where D is its mem-use beyond the shallow object.</span></div>
<div class="line"><a id="l00468" name="l00468"></a><span class="lineno">  468</span><span class="comment">   * To compute D, take each member `Y m_y` (or ptr or ref variant) of X; obtain its mem-use beyond sizeof(Y);</span></div>
<div class="line"><a id="l00469" name="l00469"></a><span class="lineno">  469</span><span class="comment">   * sum these values to get D.  Namely for each m_y:</span></div>
<div class="line"><a id="l00470" name="l00470"></a><span class="lineno">  470</span><span class="comment">   *   - It might have no non-shallow mem-use (e.g., a `float`).  0.</span></div>
<div class="line"><a id="l00471" name="l00471"></a><span class="lineno">  471</span><span class="comment">   *   - Its mem-use might be stored in a nearby data member; e.g., `char* m_str; size_t m_str_len`.</span></div>
<div class="line"><a id="l00472" name="l00472"></a><span class="lineno">  472</span><span class="comment">   *     Use that result.</span></div>
<div class="line"><a id="l00473" name="l00473"></a><span class="lineno">  473</span><span class="comment">   *   - It may itself be an aggregate object or pointer to one in which case:</span></div>
<div class="line"><a id="l00474" name="l00474"></a><span class="lineno">  474</span><span class="comment">   *     - If there is no deep_size(const Y&amp;), it has no non-shallow mem-use.  0.</span></div>
<div class="line"><a id="l00475" name="l00475"></a><span class="lineno">  475</span><span class="comment">   *     - If there is deep_size(const Y&amp;), its returned value = the result.  (If m_y is a ptr, pass *m_y as arg.)</span></div>
<div class="line"><a id="l00476" name="l00476"></a><span class="lineno">  476</span><span class="comment">   *       - deep_size() should itself follow this pattern, recursively.</span></div>
<div class="line"><a id="l00477" name="l00477"></a><span class="lineno">  477</span><span class="comment">   *     - *Either way*: If m_y is a ptr or ref (to heap), also add sizeof(Y).</span></div>
<div class="line"><a id="l00478" name="l00478"></a><span class="lineno">  478</span><span class="comment">   *</span></div>
<div class="line"><a id="l00479" name="l00479"></a><span class="lineno">  479</span><span class="comment">   * So in our case you see, when we got to Log_request, we took its sizeof() and then added its deep_size() (below).</span></div>
<div class="line"><a id="l00480" name="l00480"></a><span class="lineno">  480</span><span class="comment">   *</span></div>
<div class="line"><a id="l00481" name="l00481"></a><span class="lineno">  481</span><span class="comment">   * Rationale for pattern: Keep things organized; provide reusable deep_size() APIs where applicable.  E.g.,</span></div>
<div class="line"><a id="l00482" name="l00482"></a><span class="lineno">  482</span><span class="comment">   * deep_size(const string&amp;) may be useful elsewhere.</span></div>
<div class="line"><a id="l00483" name="l00483"></a><span class="lineno">  483</span><span class="comment">   *</span></div>
<div class="line"><a id="l00484" name="l00484"></a><span class="lineno">  484</span><span class="comment">   * Rationale: Why not include sizeof() in deep_size()?  Answer: Consider</span></div>
<div class="line"><a id="l00485" name="l00485"></a><span class="lineno">  485</span><span class="comment">   *   struct X { struct { int m_a; float m_b; } m_c; bool m_d; };  X x{ ... };</span></div>
<div class="line"><a id="l00486" name="l00486"></a><span class="lineno">  486</span><span class="comment">   * Its mem-use is simply sizeof(X).  So we get the sizeof() part, which is mandatory, for &quot;free,&quot; without having</span></div>
<div class="line"><a id="l00487" name="l00487"></a><span class="lineno">  487</span><span class="comment">   * to error-pronely enumerate members at various levels, plus the boiler-plate of needing deep_size() at each level;</span></div>
<div class="line"><a id="l00488" name="l00488"></a><span class="lineno">  488</span><span class="comment">   * and so on.  So it makes sense to separate the sizeof() part -- executed once at the top level -- and the</span></div>
<div class="line"><a id="l00489" name="l00489"></a><span class="lineno">  489</span><span class="comment">   * deep_size() part which is potentially recursive but only needs to explicitly define deep_size() for those with</span></div>
<div class="line"><a id="l00490" name="l00490"></a><span class="lineno">  490</span><span class="comment">   * non-zero non-shallow mem-use and/or ptrs/refs; and only need to mention such members (and no others) in</span></div>
<div class="line"><a id="l00491" name="l00491"></a><span class="lineno">  491</span><span class="comment">   * mem-use formulas.</span></div>
<div class="line"><a id="l00492" name="l00492"></a><span class="lineno">  492</span><span class="comment">   *</span></div>
<div class="line"><a id="l00493" name="l00493"></a><span class="lineno">  493</span><span class="comment">   * @todo We could probably get fancier with it, like having a deep_size&lt;T&gt;(const T* t) specialization that would</span></div>
<div class="line"><a id="l00494" name="l00494"></a><span class="lineno">  494</span><span class="comment">   * forward to `sizeof T + deep_size(*t)` if it exists... or something like that.  For now seems like overkill. */</span></div>
<div class="line"><a id="l00495" name="l00495"></a><span class="lineno">  495</span>} <span class="comment">// Async_file_logger::deep_size()</span></div>
<div class="line"><a id="l00496" name="l00496"></a><span class="lineno">  496</span> </div>
<div class="line"><a id="l00497" name="l00497"></a><span class="lineno"><a class="line" href="classflow_1_1log_1_1Async__file__logger.html#aaaf956d63042cbc0800680996adabfa2">  497</a></span><span class="keywordtype">void</span> <a class="code hl_function" href="classflow_1_1log_1_1Async__file__logger.html#aaaf956d63042cbc0800680996adabfa2">Async_file_logger::log_flush_and_reopen</a>(<span class="keywordtype">bool</span> async)</div>
<div class="line"><a id="l00498" name="l00498"></a><span class="lineno">  498</span>{</div>
<div class="line"><a id="l00499" name="l00499"></a><span class="lineno">  499</span>  <span class="keyword">using </span><a class="code hl_enumeration" href="namespaceflow_1_1async.html#a0a06794b16b72f2829ce3353557c8485">async::Synchronicity</a>;</div>
<div class="line"><a id="l00500" name="l00500"></a><span class="lineno">  500</span> </div>
<div class="line"><a id="l00501" name="l00501"></a><span class="lineno">  501</span>  <span class="comment">// We are in some unspecified user thread that isn&#39;t m_async_worker.</span></div>
<div class="line"><a id="l00502" name="l00502"></a><span class="lineno">  502</span> </div>
<div class="line"><a id="l00503" name="l00503"></a><span class="lineno">  503</span>  <a class="code hl_define" href="log_8hpp.html#a325fdd4b5cf0be49b37d3b7b7c29070d">FLOW_LOG_INFO</a>(<span class="stringliteral">&quot;Async_file_logger [&quot;</span> &lt;&lt; <span class="keyword">this</span> &lt;&lt; <span class="stringliteral">&quot;]: Non-worker (user) thread &quot;</span></div>
<div class="line"><a id="l00504" name="l00504"></a><span class="lineno">  504</span>                <span class="stringliteral">&quot;requested [&quot;</span> &lt;&lt; (async ? <span class="stringliteral">&quot;asynchronous&quot;</span> : <span class="stringliteral">&quot;synchronous&quot;</span>) &lt;&lt; <span class="stringliteral">&quot;] file flush/close (if needed) and &quot;</span></div>
<div class="line"><a id="l00505" name="l00505"></a><span class="lineno">  505</span>                <span class="stringliteral">&quot;re-open, such as for rotation or at initialization.&quot;</span>);</div>
<div class="line"><a id="l00506" name="l00506"></a><span class="lineno">  506</span> </div>
<div class="line"><a id="l00507" name="l00507"></a><span class="lineno">  507</span>  <a class="code hl_variable" href="classflow_1_1log_1_1Async__file__logger.html#a2cbf044c57201ea66c2c7fa0026846eb">m_async_worker</a>.<a class="code hl_function" href="classflow_1_1async_1_1Single__thread__task__loop.html#adaf7dbd5fbd6ee7c886daabc7a6ad0ae">post</a>([<span class="keyword">this</span>]() { <a class="code hl_variable" href="classflow_1_1log_1_1Async__file__logger.html#a5c06c592797c70077fc02c98ebf231da">m_serial_logger</a>-&gt;log_flush_and_reopen(); },</div>
<div class="line"><a id="l00508" name="l00508"></a><span class="lineno">  508</span>                      async ? Synchronicity::S_ASYNC : Synchronicity::S_ASYNC_AND_AWAIT_CONCURRENT_COMPLETION);</div>
<div class="line"><a id="l00509" name="l00509"></a><span class="lineno">  509</span>}</div>
<div class="line"><a id="l00510" name="l00510"></a><span class="lineno">  510</span> </div>
<div class="line"><a id="l00511" name="l00511"></a><span class="lineno"><a class="line" href="classflow_1_1log_1_1Async__file__logger.html#ad139ac22e5953e52e03648860a15e3fd">  511</a></span><span class="keywordtype">bool</span> <a class="code hl_function" href="classflow_1_1log_1_1Async__file__logger.html#ad139ac22e5953e52e03648860a15e3fd">Async_file_logger::should_log</a>(<a class="code hl_enumeration" href="namespaceflow_1_1log.html#a5c602384e6fe9d7642740ac2fae4ad04">Sev</a> sev, <span class="keyword">const</span> <a class="code hl_class" href="classflow_1_1log_1_1Component.html">Component</a>&amp; component) <span class="keyword">const</span> <span class="comment">// Virtual.</span></div>
<div class="line"><a id="l00512" name="l00512"></a><span class="lineno">  512</span>{</div>
<div class="line"><a id="l00513" name="l00513"></a><span class="lineno">  513</span>  <span class="keywordflow">if</span> (!m_serial_logger-&gt;should_log(sev, component)) <span class="comment">// In normal conditions this is likeliest to return false.</span></div>
<div class="line"><a id="l00514" name="l00514"></a><span class="lineno">  514</span>  {</div>
<div class="line"><a id="l00515" name="l00515"></a><span class="lineno">  515</span>    <span class="keywordflow">return</span> <span class="keyword">false</span>;</div>
<div class="line"><a id="l00516" name="l00516"></a><span class="lineno">  516</span>  }</div>
<div class="line"><a id="l00517" name="l00517"></a><span class="lineno">  517</span>  <span class="comment">// else</span></div>
<div class="line"><a id="l00518" name="l00518"></a><span class="lineno">  518</span> </div>
<div class="line"><a id="l00519" name="l00519"></a><span class="lineno">  519</span>  <span class="comment">/* As explained in doc header (please see there for discussion), throttling -- if on -- can prevent logging.</span></div>
<div class="line"><a id="l00520" name="l00520"></a><span class="lineno">  520</span><span class="comment">   * It is important that the following code is as fast as possible, though by placing it below the above</span></div>
<div class="line"><a id="l00521" name="l00521"></a><span class="lineno">  521</span><span class="comment">   * forwarded should_log() check we&#39;ve performed a key optimization already, as in a properly configured</span></div>
<div class="line"><a id="l00522" name="l00522"></a><span class="lineno">  522</span><span class="comment">   * system verbosity knobs should throw out most messages-to-be. */</span></div>
<div class="line"><a id="l00523" name="l00523"></a><span class="lineno">  523</span> </div>
<div class="line"><a id="l00524" name="l00524"></a><span class="lineno">  524</span>  <span class="keywordflow">if</span> (!m_throttling_active.load(std::memory_order_relaxed))</div>
<div class="line"><a id="l00525" name="l00525"></a><span class="lineno">  525</span>  {</div>
<div class="line"><a id="l00526" name="l00526"></a><span class="lineno">  526</span>    <span class="keywordflow">return</span> <span class="keyword">true</span>;</div>
<div class="line"><a id="l00527" name="l00527"></a><span class="lineno">  527</span>  }</div>
<div class="line"><a id="l00528" name="l00528"></a><span class="lineno">  528</span>  <span class="comment">// else</span></div>
<div class="line"><a id="l00529" name="l00529"></a><span class="lineno">  529</span> </div>
<div class="line"><a id="l00530" name="l00530"></a><span class="lineno">  530</span>  <span class="keyword">const</span> <span class="keyword">auto</span> throttled = m_throttling_now.load(std::memory_order_relaxed);</div>
<div class="line"><a id="l00531" name="l00531"></a><span class="lineno">  531</span> </div>
<div class="line"><a id="l00532" name="l00532"></a><span class="lineno">  532</span><span class="preprocessor">#if 0 </span><span class="comment">// Obv change to `if 1` if debugging + want to see it.  Could just use TRACE but avoiding should_log() cost.</span></div>
<div class="line"><a id="l00533" name="l00533"></a><span class="lineno">  533</span>  <a class="code hl_define" href="log_8hpp.html#a325fdd4b5cf0be49b37d3b7b7c29070d">FLOW_LOG_INFO</a>(<span class="stringliteral">&quot;Async_file_logger [&quot;</span> &lt;&lt; <span class="keyword">this</span> &lt;&lt; <span class="stringliteral">&quot;]: &quot;</span></div>
<div class="line"><a id="l00534" name="l00534"></a><span class="lineno">  534</span>                <span class="stringliteral">&quot;should_log(sev=[&quot;</span> &lt;&lt; sev &lt;&lt; <span class="stringliteral">&quot;]; component=[&quot;</span> &lt;&lt; component.payload_enum_raw_value() &lt;&lt; <span class="stringliteral">&quot;]) &quot;</span></div>
<div class="line"><a id="l00535" name="l00535"></a><span class="lineno">  535</span>                <span class="stringliteral">&quot;throttling algorithm situation (reminder: beware concurrency): &quot;</span></div>
<div class="line"><a id="l00536" name="l00536"></a><span class="lineno">  536</span>                <span class="stringliteral">&quot;Throttling feature active? = 1; throttling? = [&quot;</span> &lt;&lt; throttled &lt;&lt; <span class="stringliteral">&quot;].&quot;</span>);</div>
<div class="line"><a id="l00537" name="l00537"></a><span class="lineno">  537</span><span class="preprocessor">#endif</span></div>
<div class="line"><a id="l00538" name="l00538"></a><span class="lineno">  538</span> </div>
<div class="line"><a id="l00539" name="l00539"></a><span class="lineno">  539</span>  <span class="keywordflow">return</span> !throttled;</div>
<div class="line"><a id="l00540" name="l00540"></a><span class="lineno">  540</span>} <span class="comment">// Async_file_logger::should_log()</span></div>
<div class="line"><a id="l00541" name="l00541"></a><span class="lineno">  541</span> </div>
<div class="line"><a id="l00542" name="l00542"></a><span class="lineno"><a class="line" href="classflow_1_1log_1_1Async__file__logger.html#afd773546633aec017f2041feb3a75dd3">  542</a></span><span class="keywordtype">bool</span> <a class="code hl_function" href="classflow_1_1log_1_1Async__file__logger.html#afd773546633aec017f2041feb3a75dd3">Async_file_logger::logs_asynchronously</a>() const <span class="comment">// Virtual.</span></div>
<div class="line"><a id="l00543" name="l00543"></a><span class="lineno">  543</span>{</div>
<div class="line"><a id="l00544" name="l00544"></a><span class="lineno">  544</span>  <span class="keywordflow">return</span> <span class="keyword">true</span>;</div>
<div class="line"><a id="l00545" name="l00545"></a><span class="lineno">  545</span>}</div>
<div class="line"><a id="l00546" name="l00546"></a><span class="lineno">  546</span> </div>
<div class="line"><a id="l00547" name="l00547"></a><span class="lineno">  547</span>} <span class="comment">// namespace flow::log</span></div>
<div class="ttc" id="aasync__file__logger_8hpp_html"><div class="ttname"><a href="async__file__logger_8hpp.html">async_file_logger.hpp</a></div></div>
<div class="ttc" id="aclassflow_1_1async_1_1Single__thread__task__loop_html_adaf7dbd5fbd6ee7c886daabc7a6ad0ae"><div class="ttname"><a href="classflow_1_1async_1_1Single__thread__task__loop.html#adaf7dbd5fbd6ee7c886daabc7a6ad0ae">flow::async::Single_thread_task_loop::post</a></div><div class="ttdeci">virtual void post(Task &amp;&amp;task, Synchronicity synchronicity=Synchronicity::S_ASYNC)</div><div class="ttdoc">Cause the given Task (function) to execute within the worker thread as soon as the thread is free of ...</div><div class="ttdef"><b>Definition:</b> <a href="single__thread__task__loop_8cpp_source.html#l00061">single_thread_task_loop.cpp:61</a></div></div>
<div class="ttc" id="aclassflow_1_1log_1_1Async__file__logger_html"><div class="ttname"><a href="classflow_1_1log_1_1Async__file__logger.html">flow::log::Async_file_logger</a></div><div class="ttdoc">An implementation of Logger that logs messages to a given file-system path but never blocks any loggi...</div><div class="ttdef"><b>Definition:</b> <a href="async__file__logger_8hpp_source.html#l00358">async_file_logger.hpp:361</a></div></div>
<div class="ttc" id="aclassflow_1_1log_1_1Async__file__logger_html_a10757ede565842d0faebf50bc1424610"><div class="ttname"><a href="classflow_1_1log_1_1Async__file__logger.html#a10757ede565842d0faebf50bc1424610">flow::log::Async_file_logger::Lock_guard</a></div><div class="ttdeci">flow::util::Lock_guard&lt; Mutex &gt; Lock_guard</div><div class="ttdoc">Short-hand for Mutex lock.</div><div class="ttdef"><b>Definition:</b> <a href="async__file__logger_8hpp_source.html#l00567">async_file_logger.hpp:567</a></div></div>
<div class="ttc" id="aclassflow_1_1log_1_1Async__file__logger_html_a2cbf044c57201ea66c2c7fa0026846eb"><div class="ttname"><a href="classflow_1_1log_1_1Async__file__logger.html#a2cbf044c57201ea66c2c7fa0026846eb">flow::log::Async_file_logger::m_async_worker</a></div><div class="ttdeci">async::Single_thread_task_loop m_async_worker</div><div class="ttdoc">The thread (1-thread pool, technically) in charge of all m_serial_logger I/O operations including wri...</div><div class="ttdef"><b>Definition:</b> <a href="async__file__logger_8hpp_source.html#l00774">async_file_logger.hpp:774</a></div></div>
<div class="ttc" id="aclassflow_1_1log_1_1Async__file__logger_html_a541843c3b49c59a70aad70d8ab984188"><div class="ttname"><a href="classflow_1_1log_1_1Async__file__logger.html#a541843c3b49c59a70aad70d8ab984188">flow::log::Async_file_logger::on_rotate_signal</a></div><div class="ttdeci">void on_rotate_signal(const Error_code &amp;sys_err_code, int sig_number)</div><div class="ttdoc">SIGHUP/equivalent handler for the optional feature capture_rotate_signals_internally in constructor.</div><div class="ttdef"><b>Definition:</b> <a href="async__file__logger_8cpp_source.html#l00209">async_file_logger.cpp:209</a></div></div>
<div class="ttc" id="aclassflow_1_1log_1_1Async__file__logger_html_a5bbad8cea27134844e73daff014cc82a"><div class="ttname"><a href="classflow_1_1log_1_1Async__file__logger.html#a5bbad8cea27134844e73daff014cc82a">flow::log::Async_file_logger::m_throttling_active</a></div><div class="ttdeci">std::atomic&lt; bool &gt; m_throttling_active</div><div class="ttdoc">Whether the throttling-based-on-pending-logs-memory-used feature is currently active or not.</div><div class="ttdef"><b>Definition:</b> <a href="async__file__logger_8hpp_source.html#l00733">async_file_logger.hpp:733</a></div></div>
<div class="ttc" id="aclassflow_1_1log_1_1Async__file__logger_html_a5c06c592797c70077fc02c98ebf231da"><div class="ttname"><a href="classflow_1_1log_1_1Async__file__logger.html#a5c06c592797c70077fc02c98ebf231da">flow::log::Async_file_logger::m_serial_logger</a></div><div class="ttdeci">boost::movelib::unique_ptr&lt; Serial_file_logger &gt; m_serial_logger</div><div class="ttdoc">This is the Logger doing all the real log-writing work (the one stored in Log_context is the logger-a...</div><div class="ttdef"><b>Definition:</b> <a href="async__file__logger_8hpp_source.html#l00767">async_file_logger.hpp:767</a></div></div>
<div class="ttc" id="aclassflow_1_1log_1_1Async__file__logger_html_a6d74d81cb726a30f33f4fc106e3be5b6"><div class="ttname"><a href="classflow_1_1log_1_1Async__file__logger.html#a6d74d81cb726a30f33f4fc106e3be5b6">flow::log::Async_file_logger::mem_cost</a></div><div class="ttdeci">static size_t mem_cost(const Log_request &amp;log_request)</div><div class="ttdoc">How much do_log() issuing the supplied Log_request shall contribute to m_pending_logs_sz.</div><div class="ttdef"><b>Definition:</b> <a href="async__file__logger_8cpp_source.html#l00439">async_file_logger.cpp:439</a></div></div>
<div class="ttc" id="aclassflow_1_1log_1_1Async__file__logger_html_a7192ad2ad8de3014dba6805cd60d5166"><div class="ttname"><a href="classflow_1_1log_1_1Async__file__logger.html#a7192ad2ad8de3014dba6805cd60d5166">flow::log::Async_file_logger::m_signal_set</a></div><div class="ttdeci">Signal_set m_signal_set</div><div class="ttdoc">Signal set which we may or may not be using to trap SIGHUP in order to auto-fire m_serial_logger-&gt;log...</div><div class="ttdef"><b>Definition:</b> <a href="async__file__logger_8hpp_source.html#l00782">async_file_logger.hpp:782</a></div></div>
<div class="ttc" id="aclassflow_1_1log_1_1Async__file__logger_html_a7cce9184c2137aa4c2d09894e1aaa7c9"><div class="ttname"><a href="classflow_1_1log_1_1Async__file__logger.html#a7cce9184c2137aa4c2d09894e1aaa7c9">flow::log::Async_file_logger::m_pending_logs_sz</a></div><div class="ttdeci">size_t m_pending_logs_sz</div><div class="ttdoc">Estimate of how much RAM is being used by storing do_log() requests' data (message itself,...</div><div class="ttdef"><b>Definition:</b> <a href="async__file__logger_8hpp_source.html#l00701">async_file_logger.hpp:701</a></div></div>
<div class="ttc" id="aclassflow_1_1log_1_1Async__file__logger_html_a83cff0d6857a8295e41f90d5e9cab711"><div class="ttname"><a href="classflow_1_1log_1_1Async__file__logger.html#a83cff0d6857a8295e41f90d5e9cab711">flow::log::Async_file_logger::throttling_active</a></div><div class="ttdeci">bool throttling_active() const</div><div class="ttdoc">Whether the throttling feature is currently in effect.</div><div class="ttdef"><b>Definition:</b> <a href="async__file__logger_8cpp_source.html#l00121">async_file_logger.cpp:121</a></div></div>
<div class="ttc" id="aclassflow_1_1log_1_1Async__file__logger_html_a99cd4faff109ef35720fbed9837973dc"><div class="ttname"><a href="classflow_1_1log_1_1Async__file__logger.html#a99cd4faff109ef35720fbed9837973dc">flow::log::Async_file_logger::m_throttling_mutex</a></div><div class="ttdeci">Mutex m_throttling_mutex</div><div class="ttdoc">Protects throttling algorithm data that require coherence among themselves: m_throttling_cfg,...</div><div class="ttdef"><b>Definition:</b> <a href="async__file__logger_8hpp_source.html#l00680">async_file_logger.hpp:680</a></div></div>
<div class="ttc" id="aclassflow_1_1log_1_1Async__file__logger_html_a9eff13fef045d9dd58a34d207ff6521e"><div class="ttname"><a href="classflow_1_1log_1_1Async__file__logger.html#a9eff13fef045d9dd58a34d207ff6521e">flow::log::Async_file_logger::deep_size</a></div><div class="ttdeci">static size_t deep_size(const Log_request &amp;val)</div><div class="ttdoc">Estimate of memory footprint of the given value, including memory allocated on its behalf – but exclu...</div><div class="ttdef"><b>Definition:</b> <a href="async__file__logger_8cpp_source.html#l00457">async_file_logger.cpp:457</a></div></div>
<div class="ttc" id="aclassflow_1_1log_1_1Async__file__logger_html_aa13ef30bc2d66758c29c31dc76a130aa"><div class="ttname"><a href="classflow_1_1log_1_1Async__file__logger.html#aa13ef30bc2d66758c29c31dc76a130aa">flow::log::Async_file_logger::m_throttling_now</a></div><div class="ttdeci">std::atomic&lt; bool &gt; m_throttling_now</div><div class="ttdoc">Contains the output of the always-on throttling algorithm; namely true if currently should_log() shal...</div><div class="ttdef"><b>Definition:</b> <a href="async__file__logger_8hpp_source.html#l00720">async_file_logger.hpp:720</a></div></div>
<div class="ttc" id="aclassflow_1_1log_1_1Async__file__logger_html_aa3d544ab96299a8c2b53b7be485d1a6e"><div class="ttname"><a href="classflow_1_1log_1_1Async__file__logger.html#aa3d544ab96299a8c2b53b7be485d1a6e">flow::log::Async_file_logger::m_throttling_cfg</a></div><div class="ttdeci">Throttling_cfg m_throttling_cfg</div><div class="ttdoc">See Throttling_cfg. Protected by m_throttling_mutex.</div><div class="ttdef"><b>Definition:</b> <a href="async__file__logger_8hpp_source.html#l00683">async_file_logger.hpp:683</a></div></div>
<div class="ttc" id="aclassflow_1_1log_1_1Async__file__logger_html_aa557c0f55c1044161acc8fb54c115a3e"><div class="ttname"><a href="classflow_1_1log_1_1Async__file__logger.html#aa557c0f55c1044161acc8fb54c115a3e">flow::log::Async_file_logger::do_log</a></div><div class="ttdeci">void do_log(Msg_metadata *metadata, util::String_view msg) override</div><div class="ttdoc">Implements interface method by asynchronously logging the message and some subset of the metadata in ...</div><div class="ttdef"><b>Definition:</b> <a href="async__file__logger_8cpp_source.html#l00242">async_file_logger.cpp:242</a></div></div>
<div class="ttc" id="aclassflow_1_1log_1_1Async__file__logger_html_aaaf956d63042cbc0800680996adabfa2"><div class="ttname"><a href="classflow_1_1log_1_1Async__file__logger.html#aaaf956d63042cbc0800680996adabfa2">flow::log::Async_file_logger::log_flush_and_reopen</a></div><div class="ttdeci">void log_flush_and_reopen(bool async=true)</div><div class="ttdoc">Causes the log at the file-system path to be flushed/closed (if needed) and re-opened; this will happ...</div><div class="ttdef"><b>Definition:</b> <a href="async__file__logger_8cpp_source.html#l00497">async_file_logger.cpp:497</a></div></div>
<div class="ttc" id="aclassflow_1_1log_1_1Async__file__logger_html_ac2080e8abfc2cd9580c84626ae205010"><div class="ttname"><a href="classflow_1_1log_1_1Async__file__logger.html#ac2080e8abfc2cd9580c84626ae205010">flow::log::Async_file_logger::throttling_cfg</a></div><div class="ttdeci">Throttling_cfg throttling_cfg() const</div><div class="ttdoc">Accessor returning a copy of the current set of throttling knobs.</div><div class="ttdef"><b>Definition:</b> <a href="async__file__logger_8cpp_source.html#l00115">async_file_logger.cpp:115</a></div></div>
<div class="ttc" id="aclassflow_1_1log_1_1Async__file__logger_html_ad139ac22e5953e52e03648860a15e3fd"><div class="ttname"><a href="classflow_1_1log_1_1Async__file__logger.html#ad139ac22e5953e52e03648860a15e3fd">flow::log::Async_file_logger::should_log</a></div><div class="ttdeci">bool should_log(Sev sev, const Component &amp;component) const override</div><div class="ttdoc">Implements interface method by returning true if the severity and component (which is allowed to be n...</div><div class="ttdef"><b>Definition:</b> <a href="async__file__logger_8cpp_source.html#l00511">async_file_logger.cpp:511</a></div></div>
<div class="ttc" id="aclassflow_1_1log_1_1Async__file__logger_html_ae48ec685cc9951a37bb670dd92fe1f4e"><div class="ttname"><a href="classflow_1_1log_1_1Async__file__logger.html#ae48ec685cc9951a37bb670dd92fe1f4e">flow::log::Async_file_logger::~Async_file_logger</a></div><div class="ttdeci">~Async_file_logger() override</div><div class="ttdoc">Flushes out anything buffered, returns resources/closes output file(s); then returns.</div><div class="ttdef"><b>Definition:</b> <a href="async__file__logger_8cpp_source.html#l00177">async_file_logger.cpp:177</a></div></div>
<div class="ttc" id="aclassflow_1_1log_1_1Async__file__logger_html_aec2b1796c81b020cacea493e21e19562"><div class="ttname"><a href="classflow_1_1log_1_1Async__file__logger.html#aec2b1796c81b020cacea493e21e19562">flow::log::Async_file_logger::Async_file_logger</a></div><div class="ttdeci">Async_file_logger(Logger *backup_logger_ptr, Config *config, const fs::path &amp;log_path, bool capture_rotate_signals_internally)</div><div class="ttdoc">Constructs logger to subsequently log to the given file-system path.</div><div class="ttdef"><b>Definition:</b> <a href="async__file__logger_8cpp_source.html#l00032">async_file_logger.cpp:32</a></div></div>
<div class="ttc" id="aclassflow_1_1log_1_1Async__file__logger_html_afd773546633aec017f2041feb3a75dd3"><div class="ttname"><a href="classflow_1_1log_1_1Async__file__logger.html#afd773546633aec017f2041feb3a75dd3">flow::log::Async_file_logger::logs_asynchronously</a></div><div class="ttdeci">bool logs_asynchronously() const override</div><div class="ttdoc">Implements interface method by returning true, indicating that this Logger may need the contents of *...</div><div class="ttdef"><b>Definition:</b> <a href="async__file__logger_8cpp_source.html#l00542">async_file_logger.cpp:542</a></div></div>
<div class="ttc" id="aclassflow_1_1log_1_1Component_html"><div class="ttname"><a href="classflow_1_1log_1_1Component.html">flow::log::Component</a></div><div class="ttdoc">A light-weight class, each object storing a component payload encoding an enum value from enum type o...</div><div class="ttdef"><b>Definition:</b> <a href="log_8hpp_source.html#l00839">log.hpp:840</a></div></div>
<div class="ttc" id="aclassflow_1_1log_1_1Config_html"><div class="ttname"><a href="classflow_1_1log_1_1Config.html">flow::log::Config</a></div><div class="ttdoc">Class used to configure the filtering and logging behavior of Loggers; its use in your custom Loggers...</div><div class="ttdef"><b>Definition:</b> <a href="config_8hpp_source.html#l00316">config.hpp:317</a></div></div>
<div class="ttc" id="aclassflow_1_1log_1_1Log__context_html"><div class="ttname"><a href="classflow_1_1log_1_1Log__context.html">flow::log::Log_context</a></div><div class="ttdoc">Convenience class that simply stores a Logger and/or Component passed into a constructor; and returns...</div><div class="ttdef"><b>Definition:</b> <a href="log_8hpp_source.html#l01609">log.hpp:1610</a></div></div>
<div class="ttc" id="aclassflow_1_1log_1_1Logger_html"><div class="ttname"><a href="classflow_1_1log_1_1Logger.html">flow::log::Logger</a></div><div class="ttdoc">Interface that the user should implement, passing the implementing Logger into logging classes (Flow'...</div><div class="ttdef"><b>Definition:</b> <a href="log_8hpp_source.html#l01280">log.hpp:1284</a></div></div>
<div class="ttc" id="aerror_2error_8hpp_html_a019ee6e90802e444572dd78d312d6e23"><div class="ttname"><a href="error_2error_8hpp.html#a019ee6e90802e444572dd78d312d6e23">FLOW_ERROR_SYS_ERROR_LOG_WARNING</a></div><div class="ttdeci">#define FLOW_ERROR_SYS_ERROR_LOG_WARNING()</div><div class="ttdoc">Logs a warning about the (often errno-based or from a library) error code in sys_err_code.</div><div class="ttdef"><b>Definition:</b> <a href="error_2error_8hpp_source.html#l00269">error.hpp:269</a></div></div>
<div class="ttc" id="alog_8hpp_html_a325fdd4b5cf0be49b37d3b7b7c29070d"><div class="ttname"><a href="log_8hpp.html#a325fdd4b5cf0be49b37d3b7b7c29070d">FLOW_LOG_INFO</a></div><div class="ttdeci">#define FLOW_LOG_INFO(ARG_stream_fragment)</div><div class="ttdoc">Logs an INFO message into flow::log::Logger *get_logger() with flow::log::Component get_log_component...</div><div class="ttdef"><b>Definition:</b> <a href="log_8hpp_source.html#l00197">log.hpp:197</a></div></div>
<div class="ttc" id="alog_8hpp_html_a626c7dc4d3b4dc0b32a8aac8624d66bc"><div class="ttname"><a href="log_8hpp.html#a626c7dc4d3b4dc0b32a8aac8624d66bc">FLOW_LOG_WARNING</a></div><div class="ttdeci">#define FLOW_LOG_WARNING(ARG_stream_fragment)</div><div class="ttdoc">Logs a WARNING message into flow::log::Logger *get_logger() with flow::log::Component get_log_compone...</div><div class="ttdef"><b>Definition:</b> <a href="log_8hpp_source.html#l00152">log.hpp:152</a></div></div>
<div class="ttc" id="alog_8hpp_html_a692bbadd8b5c3e9cef7a0bbea1915e66"><div class="ttname"><a href="log_8hpp.html#a692bbadd8b5c3e9cef7a0bbea1915e66">FLOW_LOG_WITH_CHECKING</a></div><div class="ttdeci">#define FLOW_LOG_WITH_CHECKING(ARG_sev, ARG_stream_fragment)</div><div class="ttdoc">Logs a message of the specified severity into flow::log::Logger *get_logger() with flow::log::Compone...</div><div class="ttdef"><b>Definition:</b> <a href="log_8hpp_source.html#l00489">log.hpp:489</a></div></div>
<div class="ttc" id="alog_8hpp_html_ae4b5d4fdd2eb052615620879dd74af95"><div class="ttname"><a href="log_8hpp.html#ae4b5d4fdd2eb052615620879dd74af95">FLOW_LOG_SET_CONTEXT</a></div><div class="ttdeci">#define FLOW_LOG_SET_CONTEXT(ARG_logger_ptr, ARG_component_payload)</div><div class="ttdoc">For the rest of the block within which this macro is instantiated, causes all FLOW_LOG_....</div><div class="ttdef"><b>Definition:</b> <a href="log_8hpp_source.html#l00405">log.hpp:405</a></div></div>
<div class="ttc" id="anamespaceflow_1_1async_html_a0a06794b16b72f2829ce3353557c8485"><div class="ttname"><a href="namespaceflow_1_1async.html#a0a06794b16b72f2829ce3353557c8485">flow::async::Synchronicity</a></div><div class="ttdeci">Synchronicity</div><div class="ttdoc">Enumeration indicating the manner in which asio_exec_ctx_post(), and various boost....</div><div class="ttdef"><b>Definition:</b> <a href="async__fwd_8hpp_source.html#l00222">async_fwd.hpp:223</a></div></div>
<div class="ttc" id="anamespaceflow_1_1async_html_a227e64eb71ec278f19d679d8411db627"><div class="ttname"><a href="namespaceflow_1_1async.html#a227e64eb71ec278f19d679d8411db627">flow::async::reset_this_thread_pinning</a></div><div class="ttdeci">void reset_this_thread_pinning()</div><div class="ttdoc">Resets processor-affinity of the calling thread; does not log; and throws on extremely unlikely syste...</div><div class="ttdef"><b>Definition:</b> <a href="concurrent__task__loop_8cpp_source.html#l00309">concurrent_task_loop.cpp:309</a></div></div>
<div class="ttc" id="anamespaceflow_1_1async_html_af35fb65bdea1a3a92929ec2c4a6a6b72"><div class="ttname"><a href="namespaceflow_1_1async.html#af35fb65bdea1a3a92929ec2c4a6a6b72">flow::async::Task</a></div><div class="ttdeci">Function&lt; void()&gt; Task</div><div class="ttdoc">Short-hand for a task that can be posted for execution by a Concurrent_task_loop or flow::util::Task_...</div><div class="ttdef"><b>Definition:</b> <a href="async__fwd_8hpp_source.html#l00096">async_fwd.hpp:96</a></div></div>
<div class="ttc" id="anamespaceflow_1_1log_html"><div class="ttname"><a href="namespaceflow_1_1log.html">flow::log</a></div><div class="ttdoc">Flow module providing logging functionality.</div><div class="ttdef"><b>Definition:</b> <a href="async__file__logger_8cpp_source.html#l00027">async_file_logger.cpp:28</a></div></div>
<div class="ttc" id="anamespaceflow_1_1log_html_a267187e63c6355704f547d794c776747"><div class="ttname"><a href="namespaceflow_1_1log.html#a267187e63c6355704f547d794c776747">flow::log::deep_size</a></div><div class="ttdeci">size_t deep_size(const Msg_metadata &amp;val)</div><div class="ttdoc">Estimate of memory footprint of the given value, including memory allocated on its behalf – but exclu...</div><div class="ttdef"><b>Definition:</b> <a href="log_8cpp_source.html#l00281">log.cpp:281</a></div></div>
<div class="ttc" id="anamespaceflow_1_1log_html_a5c602384e6fe9d7642740ac2fae4ad04"><div class="ttname"><a href="namespaceflow_1_1log.html#a5c602384e6fe9d7642740ac2fae4ad04">flow::log::Sev</a></div><div class="ttdeci">Sev</div><div class="ttdoc">Enumeration containing one of several message severity levels, ordered from highest to lowest.</div><div class="ttdef"><b>Definition:</b> <a href="log__fwd_8hpp_source.html#l00223">log_fwd.hpp:224</a></div></div>
<div class="ttc" id="anamespaceflow_1_1log_html_a5c602384e6fe9d7642740ac2fae4ad04a4aee6034ce9dbc2b5c36f27c80abe021"><div class="ttname"><a href="namespaceflow_1_1log.html#a5c602384e6fe9d7642740ac2fae4ad04a4aee6034ce9dbc2b5c36f27c80abe021">flow::log::Sev::S_WARNING</a></div><div class="ttdeci">@ S_WARNING</div><div class="ttdoc">Message indicates a &quot;bad&quot; condition that is not frequent enough to be of severity Sev::S_TRACE.</div></div>
<div class="ttc" id="anamespaceflow_1_1log_html_a5c602384e6fe9d7642740ac2fae4ad04ac238793326fae17afcc849e96b96e8e7"><div class="ttname"><a href="namespaceflow_1_1log.html#a5c602384e6fe9d7642740ac2fae4ad04ac238793326fae17afcc849e96b96e8e7">flow::log::Sev::S_INFO</a></div><div class="ttdeci">@ S_INFO</div><div class="ttdoc">Message indicates a not-&quot;bad&quot; condition that is not frequent enough to be of severity Sev::S_TRACE.</div></div>
<div class="ttc" id="anamespaceflow_1_1util_html_a685b86585da2fa5186f51854e7ae1561"><div class="ttname"><a href="namespaceflow_1_1util.html#a685b86585da2fa5186f51854e7ae1561">flow::util::ostream_op_string</a></div><div class="ttdeci">std::string ostream_op_string(T const &amp;... ostream_args)</div><div class="ttdoc">Equivalent to ostream_op_to_string() but returns a new string by value instead of writing to the call...</div><div class="ttdef"><b>Definition:</b> <a href="util_2util_8hpp_source.html#l00381">util.hpp:381</a></div></div>
<div class="ttc" id="anamespaceflow_1_1util_html_ae4dc52186797094b3040379ff19124c9"><div class="ttname"><a href="namespaceflow_1_1util.html#ae4dc52186797094b3040379ff19124c9">flow::util::String_view</a></div><div class="ttdeci">Basic_string_view&lt; char &gt; String_view</div><div class="ttdoc">Commonly used char-based Basic_string_view. See its doc header.</div><div class="ttdef"><b>Definition:</b> <a href="string__view_8hpp_source.html#l00191">string_view.hpp:191</a></div></div>
<div class="ttc" id="anamespaceflow_html_a29eaaa9d0fac4ce87d8b969222dbed09"><div class="ttname"><a href="namespaceflow.html#a29eaaa9d0fac4ce87d8b969222dbed09">flow::Error_code</a></div><div class="ttdeci">boost::system::error_code Error_code</div><div class="ttdoc">Short-hand for a boost.system error code (which basically encapsulates an integer/enum error code and...</div><div class="ttdef"><b>Definition:</b> <a href="common_8hpp_source.html#l00508">common.hpp:508</a></div></div>
<div class="ttc" id="anamespaceflow_html_a3938730ab4b89daf13d027a5f620e7ce"><div class="ttname"><a href="namespaceflow.html#a3938730ab4b89daf13d027a5f620e7ce">flow::Flow_log_component</a></div><div class="ttdeci">Flow_log_component</div><div class="ttdoc">The flow::log::Component payload enumeration comprising various log components used by Flow's own int...</div><div class="ttdef"><b>Definition:</b> <a href="common_8hpp_source.html#l00637">common.hpp:638</a></div></div>
<div class="ttc" id="aserial__file__logger_8hpp_html"><div class="ttname"><a href="serial__file__logger_8hpp.html">serial_file_logger.hpp</a></div></div>
<div class="ttc" id="astructflow_1_1log_1_1Async__file__logger_1_1Log__request_html"><div class="ttname"><a href="structflow_1_1log_1_1Async__file__logger_1_1Log__request.html">flow::log::Async_file_logger::Log_request</a></div><div class="ttdoc">In addition to the task object (function) itself, these are the data placed onto the queue of m_async...</div><div class="ttdef"><b>Definition:</b> <a href="async__file__logger_8hpp_source.html#l00610">async_file_logger.hpp:611</a></div></div>
<div class="ttc" id="astructflow_1_1log_1_1Async__file__logger_1_1Log__request_html_a43b7a817420a80d955e4acfd0ec10f45"><div class="ttname"><a href="structflow_1_1log_1_1Async__file__logger_1_1Log__request.html#a43b7a817420a80d955e4acfd0ec10f45">flow::log::Async_file_logger::Log_request::m_msg_size</a></div><div class="ttdeci">size_t m_msg_size</div><div class="ttdoc">Number of characters in m_msg_copy pointee string.</div><div class="ttdef"><b>Definition:</b> <a href="async__file__logger_8hpp_source.html#l00618">async_file_logger.hpp:618</a></div></div>
<div class="ttc" id="astructflow_1_1log_1_1Async__file__logger_1_1Log__request_html_a7215d35008420d5c3357df1b06761d64"><div class="ttname"><a href="structflow_1_1log_1_1Async__file__logger_1_1Log__request.html#a7215d35008420d5c3357df1b06761d64">flow::log::Async_file_logger::Log_request::m_metadata</a></div><div class="ttdeci">Msg_metadata * m_metadata</div><div class="ttdoc">Pointer to array of characters comprising a copy of msg passed to do_log(). We must delete it.</div><div class="ttdef"><b>Definition:</b> <a href="async__file__logger_8hpp_source.html#l00621">async_file_logger.hpp:621</a></div></div>
<div class="ttc" id="astructflow_1_1log_1_1Async__file__logger_1_1Throttling__cfg_html"><div class="ttname"><a href="structflow_1_1log_1_1Async__file__logger_1_1Throttling__cfg.html">flow::log::Async_file_logger::Throttling_cfg</a></div><div class="ttdoc">Controls behavior of the throttling algorithm as described in Async_file_logger doc header Throttling...</div><div class="ttdef"><b>Definition:</b> <a href="async__file__logger_8hpp_source.html#l00376">async_file_logger.hpp:377</a></div></div>
<div class="ttc" id="astructflow_1_1log_1_1Async__file__logger_1_1Throttling__cfg_html_a72a52accb11b29307dad69748e133818"><div class="ttname"><a href="structflow_1_1log_1_1Async__file__logger_1_1Throttling__cfg.html#a72a52accb11b29307dad69748e133818">flow::log::Async_file_logger::Throttling_cfg::S_HI_LIMIT_DEFAULT</a></div><div class="ttdeci">static constexpr uint64_t S_HI_LIMIT_DEFAULT</div><div class="ttdoc">Value of Async_file_logger(...).throttling_cfg().m_hi_limit: default/initial value of m_hi_limit.</div><div class="ttdef"><b>Definition:</b> <a href="async__file__logger_8hpp_source.html#l00393">async_file_logger.hpp:393</a></div></div>
<div class="ttc" id="astructflow_1_1log_1_1Async__file__logger_1_1Throttling__cfg_html_a7a30343e388c65594d06baed25b1aaa9"><div class="ttname"><a href="structflow_1_1log_1_1Async__file__logger_1_1Throttling__cfg.html#a7a30343e388c65594d06baed25b1aaa9">flow::log::Async_file_logger::Throttling_cfg::m_hi_limit</a></div><div class="ttdeci">uint64_t m_hi_limit</div><div class="ttdoc">The throttling algorithm will go from Not-Throttling to Throttling state if and only if the current m...</div><div class="ttdef"><b>Definition:</b> <a href="async__file__logger_8hpp_source.html#l00385">async_file_logger.hpp:385</a></div></div>
<div class="ttc" id="astructflow_1_1log_1_1Msg__metadata_html"><div class="ttname"><a href="structflow_1_1log_1_1Msg__metadata.html">flow::log::Msg_metadata</a></div><div class="ttdoc">Simple data store containing all of the information generated at every logging call site by flow::log...</div><div class="ttdef"><b>Definition:</b> <a href="log_8hpp_source.html#l01040">log.hpp:1041</a></div></div>
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